New York, an already-jittery city transformed by the coronavirus pandemic and protests against police brutality and systemic racism, now has its own cacophonous soundtrack: illegal fireworks being set off in soaring numbers from late afternoon until the wee hours of the morning.

For some people, the fireworks serve as a release after months of boredom and seclusion in cramped apartments. For others, they are a celebration of hard-fought strides made during the demonstrations, and a show of defiance toward the police.

But not everyone is enamored by the pyrotechnics. In the first half of June, 1,737 complaints about fireworks came into the city’s 311 system, 80 times as many as the 21 in the same period last year.

“These are not your normal kids playing with fireworks,” said Michael Ford, a piano teacher in Manhattan’s Inwood neighborhood. “These are real explosives, like Macy’s-style fireworks.”

Mr. Ford said that those who were firing off the explosives made it impossible for him to walk his dogs at night.

“People scream out their windows at them, but they just laugh,” he said, adding that he and his neighbors had called 911 as well as 311, but that the police had not responded.

“I think it’s a lot of people who have been pent-up and need to blow off steam,” he continued. “But it’s just adding whole other layer of anxiety.”

In Brooklyn’s gentrifying Flatbush section — which has recorded hundreds of complaints, among the most of any neighborhood in the city — the daily fireworks are exposing divisions over race and class, and provoking debates about what should be reported to the police.

In Harlem, the noise lasts until 1 a.m., and ranges from the pops of firecrackers to the booms of louder rockets. An officer who answered the phone at the 32nd Precinct station house on Wednesday night said that the police were being inundated with complaints.

“It’s as bad as anything I can remember,” said Adrian Benepe, a former city parks commissioner who lives on the Upper West Side.

“The police have had their hands full with major issues — demonstrations, looting and Covid — and they just don’t have the time to respond to quality-of-life issues like this,” Mr. Benepe said.

As of Thursday, the Police Department said it had made 26 seizures of fireworks and eight arrests and had issued 22 fireworks-related summonses so far this year. There have also been 5,947 firework-related 911 calls, compared with 1,590 for the same period in 2019.

The department would not comment on the current enforcement of fireworks laws.

While they are illegal to buy, sell or ignite in New York, fireworks are an entrenched tradition of the city’s streets, especially in working-class neighborhoods. They are generally sold from duffel bags or car trunks and set off in the days before July 4.

But this year, the unauthorized displays began at least a month earlier than usual, as other warm-weather get-togethers were halted by social-distancing rules.

And because of the virus outbreak, it remained unclear what the city’s traditional Macy’s 4th of July Firework Show would look like this year.

As measured by community board district, Flatbush and Inwood had the most 311 complaints about fireworks in the first half of June: 421 in Flatbush, up from two in the same period last year, and 250 in Inwood, up from just one.

On Monday evening in Flatbush, onlookers gathered to watch rockets that soared above rooftops and exploded in bursts of color. Ashley Rios, 27, and Kenya Smith, 26, sat on a stoop with their young daughters, who were not scared by the thunderous booms.

“They’re the ones that wanted to come out and see them,” Ms. Rios said.

But other residents said the fireworks were adding to the city’s unrest, while depriving them of sleep, upsetting pets and posing a safety issue. Messages posted on social media attested to such attitudes.

“Does Astoria sound like a war zone to anyone else?” one Queens resident tweeted recently.

This year, setting off fireworks in June has extra meaning, said a young man who was launching rockets with three friends on Wednesday night in Brooklyn’s Crown Heights section.

“We’re basically celebrating the fact that we survived” the coronavirus and the quarantine, said the man, Djani, 24, who asked to be identified by only his first name because of the illicit nature of what he was doing.

“You know when you have a storm and finally the rain is letting up?” he said. “I guess it’s comparable to letting out of some aggression. People have been inside.”

He also said the fireworks were a sign of defiance toward the police, “because this is illegal but we’re still doing it.”

When a young woman approached Djani and his friends, asking them to stop because the noise was disrupting her sleep and frightening her dog, they complied.

The night before, a video emerged of a fireworks display seemingly set off by firefighters in the same Brooklyn neighborhood. The Fire Department said it was investigating the matter.

The pyrotechnics have taken a physical toll, as well.

Early Wednesday in the Bronx, police officers responding to a report of gunshots instead found a teenager who had been struck in the chest while lighting off fireworks. He was hospitalized in stable condition.

In Brooklyn, a 33-year-old man was igniting fireworks inside his apartment around 5 a.m. Wednesday when a rocket backfired and struck him, the police said. He was in the hospital in critical condition.

The city has a long and storied history of illicit fireworks. For decades, Inwood residents have gathered around Dyckman Street for an unsanctioned competition among neighborhood blocks that mixes rebellion with celebration.

In the 1970s and 1980s, one of the largest fireworks displays in the city could be found in Ozone Park, Queens, where it was the highlight of the lavish Fourth of July block parties funded by the mob boss John J. Gotti outside his social club.

The Dyckman competitions have continued to grow over the years, said Stephen Feldheim, the president of the 34th Precinct Community Council, who described them as “a cat-and-mouse game” between the participants and the police.

The Inwood fireworks have “increased significantly” this year, Mr. Feldheim said.

“It’s been going on for weeks, since the beginning of June,” he said, adding that police officers might be reluctant to respond to fireworks complaints now because “they’ll be targeted for police violence and not be backed by City Hall and the district attorneys for doing their job.”

“City Hall doesn’t consider fireworks real crime anymore,” Mr. Feldheim added. “So these guys can blow stuff up and get off scot-free.”

Contacted about the fireworks surge, a spokeswoman for Mayor Bill de Blasio said that officials had “noticed an increase in incidents” and would “work with communities across the city and the N.Y.P.D. to address this serious safety issue.”

In Flatbush, the fireworks have raised questions about gentrification.

When police officers showed up last weekend to crack down on the explosives in a part of the area with many black and Hispanic residents, some people assumed it was a response to a petition created by residents of Ditmas Park, a historic district in the neighborhood, that urged the city to put a “a peaceful stop to the illegally launched fireworks that have been disrupting our sleep and our lives for weeks.”

Equality for Flatbush, which calls itself a “people of color-led, multinational grass-roots organization that does anti-police repression, affordable housing and anti-gentrification/anti-displacement organizing,” lashed out at a now-deleted Facebook group, Peaceful Ditmas Park, and a law professor who helped write the petition.

Equality for Flatbush said Peaceful Ditmas Park was “a majority-white Facebook group where pro-gentrification and white supremacist sentiment is highly prevalent” and called the law professor, Irina Manta, a “Ditmas Park Karen,” using what has become shorthand for an entitled white woman.

The organization also put out a statement calling summertime fireworks “a culturally accepted norm of Brooklyn” and “an act of resistance and a show of solidarity with the global #BlackLivesMatter rebellion.”

Ms. Manta, a Hofstra University law professor, said in a brief interview that the petition had called for civilians or mediators, not the police, to bring a stop to the fireworks. She said that the petition was never submitted to city officials, and that she never contacted the police or mayor’s office.

Ms. Manta said she had received a death threat and harassing phone calls.

The fireworks are likely to continue.

In the Bedford-Stuyvesant section of Brooklyn on Thursday, a young man who had just set off a rocket advised onlookers to return on Friday night for more.

Jeffery C. Mays and Sean Piccoli contributed reporting.