@MyAenan could you please DM me the wallet payment id from your brave://rewards-internals page on Brave? And I can take a closer look
The same happen to me today.
I had around 1.5 BAT, and it went down to about 0.3.
STATUS UPDATE: We have identified https://github.com/brave/brave-browser/issues/13601 where if our servers are experiencing technical problems the reported “Estimated pending rewards” may show an incorrect value.
There is another bug for users who run multiple-browsers with the same wallet which we are investigating.
Rest assured the above bugs do not lose any BAT.
Refreshing the brave://rewards page or restarting the browser for these bugs should restore the correct balance.
If not, it would be great if you could reach out to me at firstname.lastname@example.org so I can help diagnose the cause of your issue.