@rif You have my sympathy. I've been seeing this more and more with websites. My bank doesn't like Opera, Facebook is now showing this version (or this browser) is no longer supported, xfinity sometimes has problems, and there are others. It is strange because other, less common browsers, like Vivaldi, Brave, and DuckDuckGo work fine.
Is it something in the User Agent that Opera sends to websites? These other browsers use the Google engine, so that doesn't sseem to be the issue and, if you use a user agent switcher, that seems to help. So it seems that the info Opera is sending to these website is the problem.
I've been using Opera since version 1, and it has only been in the last few updates (maybe since 114 or so), that these problems have become more frequent.