Right now, Poland isn’t supported for Brave rewards verification, so that’s the reason for you not being able to link Uphold/Gemini. Sharing the link for supported me countries below->
Brave is working on getting workable regions back by the end of the year, so you’ll have to wait till your region is supported, to be able to link. You will still earn BATs and you’ll have to claim them each month which will be saved on your device local files. So make sure not to format, clear data or reinstall Brave as that would make you lose your BATs. Hope this helps!
Also updates about this is on the page I’m sharing below →