Since updating Opera to version 84.0.4316.21 a few hours ago, I started having problems with any Google related pages. For example, with mail.google.com, all I would see was the subject line in any email. The message field was completely blank.
After trying various things, I disabled the uBlock Origin extension and that sorted things. When I enabled it again, the same problems returned.
I have now reinstalled the extension and everything seems fine. Maybe mine was just an isolated case, but I thought I would just mention in case anyone else is puzzled by similar issues since the update.