@leland359 Apparently its only a 45 day trial tho, did you manage to find a more permanent solution?
Details:
I have a LogitechGPROX-Superlight and also have the same problem. g4 and g5(back and forward) are switched but only on Opera. It works perfectly fine elsewhere on my mac. This is for sure an Opera issue and not a mouse issue. The mouse works as intended.
Really sucks that these button functionality might be the reason I don't switch over from Brave tbh..