Why does Brave Grants withdraw BAT from my Gemini account?

It seems that Brave Grants withdraws BAT from my Gemini account after each deposit. Why is it the case? How can I prevent this from happening? How can I get back these BAT?

Version 1.34.80 Chromium: 97.0.4692.71
Wallet verified. Latest check 01/12/2022

Thanks for your help