The tobacco company Reynolds American donated $5 million to a super PAC backed by President Trump last month, about one week before his administration rolled out a new policy that could prove lucrative to the tobacco industry.

The donation, which came through a Reynolds subsidiary and brings to $8 million the total donated by the subsidiary to MAGA Inc., the Trump-backed super PAC, was revealed in a campaign finance report filed Wednesday night.

The donation came on April 30.

Two days later, a top executive at Reynolds and two lobbyists who represent the company had lunch with Mr. Trump at his golf club in Jupiter, Fla. Also attending were two executives from Altria, another tobacco company.

At the lunch, the tobacco industry representatives expressed dissatisfaction with the way the Food and Drug Administration was regulating the industry, as The New York Times reported last week.

Mr. Trump interrupted the conversation to call Dr. Marty Makary, the F.D.A. commissioner.

When Mr. Makary did not answer, the president dialed Dr. Makary’s boss, Health Secretary Robert F. Kennedy Jr., and another top health official, Dr. Mehmet Oz, the head of the Centers for Medicare and Medicaid Services.

The president complained to the men about the F.D.A.’s regulation of e-cigarettes, according to three people briefed on the meeting who were not authorized to discuss it.

Less than one week later, the F.D.A. issued new guidance that could pave the way for major tobacco companies to begin selling flavored vapes and to snare a chunk of the $6 billion e-cigarette market away from illegal Chinese competitors.

The new policy, which bypassed the F.D.A.’s regular rule-making process, also could allow higher nicotine levels in nicotine pouches. It includes a pledge to prioritize efforts to stop the import of illegal foreign vapes, an idea that has bipartisan support in Congress.

Four days after it was announced, Dr. Makary resigned, telling associates he could not in good conscience remain the head of an agency that backed such a policy.

There is no definitive evidence linking the new F.D.A. guidance to the lunch, the donation or specific lobbying. But the episode represented a victory for an industry that mostly had been on the defensive for years.

Kush Desai, a spokesman for the White House, suggested that the donation had nothing to do with the administration’s shift in vape policy.

“The only guiding factor behind the Trump administration’s health policymaking is gold standard science,” he said in a statement. He added that the F.D.A.’s regulatory treatment of vapes and nicotine pouches “is rooted in recent evidence that has found they can help adults quit smoking.”

Reynolds did not respond to a request for comment on Wednesday night.

Alex Pfeiffer, a spokesman for MAGA Inc., said in a statement that the PAC “is pleased to accept legal contributions from those who agree with President Trump’s America First agenda and his goal to make America great again.”

MAGA Inc., which is run by Mr. Trump’s allies and raises money to support aligned candidates, reported raising a total of $9.6 million last month.

The super PAC also received contributions of $1 million each from a division of the private prison firm Geo Group, the Republican megadonor Marlene Ricketts and two other donors.

Reynolds has gone all in behind Mr. Trump.

The subsidiary donated $10 million to a separate super PAC backing Mr. Trump’s campaign, according to earlier campaign finance filings. And the company donated to the effort to raise private funds to build a White House ballroom. A Reynolds executive was invited to a dinner at the White House in October hosted by Mr. Trump for donors who gave $2.5 million or more.

The president has delivered for the industry.

On Mr. Trump’s second full day in office, his administration withdrew the proposed ban on menthol cigarettes, an initiative the Biden administration had already mostly abandoned. Mr. Trump’s team also set aside a Biden-era proposal to sharply restrict nicotine in cigarettes, an effort meant to speed the transition away from a product known to be deadly.

The new guidance on flavored vapes could help companies like Reynolds gain market share considered central to the survival of the industry as cigarette sales wane.