Gemini is USA only. The exception to this is if you’re using a Rewards profile that was connected to Gemini before this change. Changing profiles, uninstalling and reinstalling Brave, adding new device, etc all would not count and would fall under current rules that say you can’t use Gemini.
If this is the notice you get, then your settings show you are in Russia. You really should check the link SmartyAadi provided. I will also link to you again. Please click and read it in its entirety. PSA: Current FAQ - #16 by Saoiray Once you change Locale so it doesn’t show Russia for country or regional format, you should be good.