It might reduce scrutiny, but not completely prevent it.
Clayton act says
"No person engaged in commerce or in any activity affecting commerce shall acquire, directly or indirectly, the whole or any part of the stock or other share capital and no person subject to the jurisdiction of the Federal Trade Commission shall acquire the whole or any part of the assets of another person engaged also in commerce or in any activity affecting commerce, where in any line of commerce or in any activity affecting commerce in any section of the country, the effect of such acquisition may be substantially to lessen competition, or to tend to create a monopoly."
Yeah 50% may have triggered antitrust
It does seem likely that the deal was at least partially structured to avoid antitrust scrutiny but my impression is that under the DMA/DSA (I can never keep track of which is which) in Europe Meta is technically a gatekeeper and has different obligations so I'll be curious to see what happens there
If this is marketed as a strategic acquisition for the national interest of the US tech industry in order to counter-act the Chinese trying to catch up on AI then nothing of the sorts will happen.