Make it illegal. Make it illegal for local advertisers to do business with them. Sanction individuals that cannot be locally prosecuted. Sanction the company.

It's already a requirement that to operate in Brazil they need local representation. Someone local who can be prosecuted, even if it's just a proxy - I'm hazy on the details but I remember reading about this at one point when they went after Twitter.

Is it going to fully stop Brazilians from using the service? Most likely not, but it will almost certainly reduce their usage, and the remaining users become a less profitable product to Meta, since they're not going to see ads for companies they can actually spend money on.

This changes incentives and may well be enough to make Meta rethink their policies. Or not, but then its effects can be measured and adjusted.