This is now totally anecdotal evidence and maybe also totally unrelated (as in that Brave browser the Bitwarden browser extension is not even installed). But yesterday, I helped my father with his online banking, which was done on Brave (Win 11 system). And we were not directly logged out, but with every step – even if it was seconds apart from each other – the online banking system required a new authentication as “it was expired” or whatever it showed exactly. (later I found out, he mainly uses Firefox now again, and probably never experienced this issue on Brave himself)
I found that really odd – and I have no idea if my father changed some settings in Brave causing this (and we’ll never know, because if I’d ask him, I’m sure he would just claim “I didn’t do anything!”).
So, thinking of that incident yesterday, I wouldn’t rule out that it could be some change or current bug (?) in Brave.