Adobe isn't (ostensibly) trying to monopolize though, they're trying to buy another company.
Regulators step in and say "That would be a monopoly", to which everyone involved says "Darn, well we can't continue trying to merge then, since that would be a felony".
This all seems totally fine and legal and working as designed.
Everyone suspects they're buying Figma for $20B not because they think it will bring that amount of money, but that it will maintains Adobe's pricing power.
Is that turns out to be true, then it seems a violation of the act.
Yes, Adobe is trying to buy their competition into submission to protect their SAAS model.
I don't think their moat is defensible indefinitely for the cost they're asking, but this type of thing would buy them some time.
It is telling that they can't do something better with the 20bil, though. Not much innovation left to squeeze out and there's no chance Figma generates this type of revenue for years (if ever?).