Hey there. Can you let us know what your autofill settings look like for Bitwarden? (A screenshot would be ideal - here are steps on how to attach one in the forum: https://discuss.grapheneos.org/d/72-discussion-forum-markdown-syntax-and-image-support-via-our-media-proxy)
What I think is likely happening here is that you were using Bitwarden's accessibility setting for Autofill, and stopped using it when Vanadium got Autofill support, which made it stop working on Brave.
EDIT: My theory seems very likely after finding this - https://github.com/brave/brave-browser/issues/25955
My guess is that you were using the accessibility option for Bitwarden, which Vanadium no longer needs because it has proper Autofill support, and when you disabled that option, you lost the ability to do Autofill in Brave.
Marking as solved as this is likely the cause. If it isn't, let us know.