I have noticed on at least two of my systems where I use Brave as default, that BAT rewards have suddenly reduced (note, prior to end of month re-set). The most notable was reaching about 1.6 BAT on my account only to log in the following day and it had dropped my amount to 0.15 BAT. I am quite new to Brave and have yet to see if the reward amounts are going to be deposited into the Brave wallet (by 07 Jan). The issue here is apparently losing BAT whilst still within the same month (Dec 2021).
Latest Brave browser
No VPN (on this particular machine)