Hello – do you happen to have Chrome installed? If so, does the same thing happen there?
What about extensions, if you have any installed, can you try disabling them?
If you need to go further than that, I would also try in a Private window, and in a new profile.
It sounds an awful lot like some behavior we’ve seen reported earlier that was from a malicious extension or local proxy. (The Chrome vs. Brave question is intended to try ferreting out the latter.)