@operanana If you downloaded your Opera version from a genuine Opera website, neither it nor its installer will contain a virus - Opera runs a tight ship with their servers. In that case, it's a 'false positive' detection on the part of the antivirus you're using (these are continually being updated and their detection schemes being altered by their makers). Since some recent update to the AV is causing the issue, the AV maker (in this case, Malwarebytes) is who you need to inform and apply pressure regarding their recent AV update.
