I will be interested in how this plays out. I believe it's Section 230 [0] that allows US platforms to not be held liable. I'd be keen to understand whether this effectively bans social media (and comment sections?) from Brazil, or whether people need to click an I-promise-I'm-not-Brazilian button to access them.
[0] Not a lawyer so wikipedia is the best I have - https://en.wikipedia.org/wiki/Section_230
Brazilian here. We still don't know if small things like comment sections and personal blogs will be under the new rules as our supreme court hasn't made any explicit exemption but their debates on the topic focused only on big techs. There is a chance an appeal will be filed to seek this kind of clarification.
As for buttons "I promisse I'm not Brazilian", that wouldn't really fly if the company in question has a lot of users in Brazil.
I suspect that we will see government enforcement only against big techs (especially Facebook, Instagram, Twitter, and YouTube).
I genuinely doubt there will be many lawsuits targeting small websites because there isn't money to be made off them. So any litigation here will probably be restricted to personal revenge cases or something like it.
I really wish this had been settled in Congress with more cleat rules and language instead of decided by the courts.