While Meta adjusts, some small businesses have begun seeking other avenues for ads. Shawn Baker, the owner of Baker SoftWash, an exterior cleaning company in Mooresville, N.C., said it previously took about $6 of Facebook ads to identify a new customer. Now it costs $27 because the ads do not find the right people, he said.

Mr. Baker has started spending $200 a month to advertise through Google’s marketing program for local businesses, which surfaces his website when people who live in the area search for cleaners. To compensate for those higher marketing costs, he has raised his prices 7 percent.

“You’re spending more money now than what you had to spend before to do the same things,” he said.

Other tech giants with first-party information are capitalizing on the change. Amazon, for example, has reams of data on its customers, including what they buy, where they reside, and what movies or TV shows they stream.

In February, Amazon disclosed the size of its advertising business — $31.2 billion in revenue in 2021 — for the first time. That makes advertising its third-largest source of sales after e-commerce and cloud computing. Amazon declined to comment.

Amber Murray, the owner of See Your Strength in St. George, Utah, which sells stickers online for people with anxiety, started experimenting with ads on Amazon after the performance of Facebook ads deteriorated. The results were remarkable, she said.

In February, she paid about $200 for Amazon to feature her products near the top of search results when customers looked up textured stickers. Sales totaled $250 a day and continued to grow, she said. When she spent $85 on a Facebook ad campaign in January, it yielded just $37.50 in sales, she said.

“I think the golden days of Facebook advertising are over,” Ms. Murray said. “On Amazon, people are looking for you, instead of you telling people what they should want.”