I am having the exact same issue and I am beyond frustrated. If this is not fixed I may switch from Brave altogether because this makes me want to pull my hair out. This only happens in some of my Brave profiles but not others, even though they have the exact same settings.
However, it appears that it may not just affect ChatGPT, as I have a similar issue with logging into Claude. I am in Kentucky and have confirmed that my IP is showing the correct location when using this browser. For the record, I do have a VPN (Aura) but it is completely off.
I have cleared my browser cache and cookies, restarted, created an entirely new Brave profile (though I did import my bookmarks, as a profile without them would be useless), turned off shields for the sites, and nothing has worked! Please tell me someone can help