@leocg I don't have extensions. The only extension is the built-in ad blocker.
My antivirus is always "on".
As I said, it's something from the Opera Browser itself. I found it in the file C: > User > [USER] > AppData > Local > Programs > Opera > 104.0.4944.33 > resources > default_partner_content.json
It should be written "bing" and only "bing", I don't understand what is that "_attributed_ysrcunow" and I don't want it.