On Dec. 18, a $20 billion deal by Adobe, the software giant, to buy Figma, a San Francisco start-up darling, fell apart

after more than a year of regulatory scrutiny.

In a blog post that day, Dylan Field, Figma’s chief executive and co-founder, painted an optimistic picture of what would come next. “Figma’s best, most innovative days are still ahead,” he wrote.

Behind the scenes, the start-up, a design platform, is picking up the pieces. In recent weeks, Figma said it had reset its internal valuation to $10 billion — half of what Adobe planned to pay for it. Some employees, who were set to reap enormous windfalls, are deflated. Figma offered severance to workers who wanted to quit, with just over 4 percent, or around 52 workers, taking the offer, said Michael Amodeo, a company spokesman.

Figma is also grappling with a tech industry that has been changed by a frenzy over artificial intelligence. It is trying to continue a breakneck pace of expansion to win customers, recruit new workers and appease investors, according to 15 current and former employees and investors, many of whom declined to be named because of nondisclosure agreements.

“It really does feel like the rug got pulled out from underneath you,” said Jason Pearson, who left Figma in 2021 and owns company stock.

Figma is a case study of what happens when a start-up on the cusp of being bought confronts newly assertive regulators — and the deal collapses.