Fines like this only work if they're large enough to change behavior. $375M for a company Meta's size is more of an accounting entry than a deterrent.
Also, “the total civil penalty of $375m was reached after the jury decided there were thousands of violations of the act, each with a maximum penalty of $5,000. Meta is also involved in a separate trial in Los Angeles, in which a young woman claims that she became addicted to platforms like Instagram and YouTube, owned by Google, as a child because of how they are intentionally designed.
There are thousands of similar lawsuits winding their way through the US courts.”
“The jury found that Meta was responsible for violating New Mexico's Unfair Practices Act because it misled the public about the safety of its platforms for young users.”
So the penalty is for misleading around CSAM. Not CSAM per se. (My understanding is the latter are still being adjudicated.)