I don't think "the government" does anything unless someone complains. In this case, the process is to send a letter requesting a "Business Review" [1]. It's probably a "fill out this simple 30 page form, wait 2.5 years (max!) and then have your review request politely declined" situation, but I suppose it's foolish to complain before trying. It feels like one of those processes that costs lawyer money that another business would usually pay for; however it's not clear what business would pay for this - maybe a heavy user of Figma? But then even if you 'win' and stop the sale, doesn't that alienate you from the founders?

1 - https://www.justice.gov/atr/business-reviews

It is. Unfortunately our laws against anti-competitive behaviours are very weak.

It's not anti-competitive because there are plenty of other options available (and anyone can go and make their own if they're willing to invest the time).

Anti-competitive would assume that there's no other viable option or means for replacement.

FWIW, I think Adobe is a shit company but calling daddy government in to thump them for (presumably) taking away or breaking the favorite toy sets a terrible precedent. If anything, this is pro-competitive because it should light a fire under the ass of indie's to replace it (which is already underway by the looks of Penpot).

Acquiring a competitor isn't going to automatically trigger antitrust laws. For one, web design is so far from critical infrastructure that it's just unlikely to be on their radar. And secondly, there's still a ton of competition. Even if Adobe and Figma are the two leaders, there's still loads of alternatives available. You can still use Sketch or Canva or any of the all-in-one beginner tools like Squarespace.