There's no indication that it's a yet-to-be-introduced requirement that will block 100+ countries including the user's own - and a footnote in the sidebar would not be the appropriate place for that.

If it's being sold in their country, works for their friends, and works for months after they purchased it - I think most people won't have reason to think twice about it (if they noticed it in the first place), or just be given the impression that the account is something handled automatically in the background.

Even if the notice clearly and correctly stated "We're taking payment from people in your country, but will prevent it being played in a few months", I think people are right to protest arbitrary enshittification of purchased products.