It's still same in the latest stable bulid 991. Not sure if they are gonna fix this in the future but in the meantime this is a workaround (use at your own risk!).

Add this at the end of the shortcut command line --ignore-certificate-errors

eg. "C:\Program Files\Opera\launcher.exe" --ignore-certificate-errors

Kinda defeat the purpose of supposedly increased security by not giving an option for the average user to decide that the site is safe to proceed. Now we gotta disable all certificate warnings just great!