Flash Disabled by Default (Target: Chrome 76+ - July 2019)
Flash will be disabled by default, but can be enabled in Settings at which point explicit permission is still required for each site
You will need to allow Flash on sites every time you start Opera.
This hasn't been my experience. When I first started poking around forums looking for a solution, the question of whether flash was enabled or not came up. When I checked on it, I saw that it was already enabled and I had never fooled with it before. And it has remained that way with no sites excluded ever since, except when I explicitly disabled it while experimenting. Possibly that is a characteristic unique to the rpm distribution.
If the last suggestion hadn't worked, I was going to uninstall Opera and try the snap version. It would be interesting to see if it has the same problem.
The thing that puzzles me in all of this discussion is why it's even necessary to go through all of this to enable a feature which is used all over the Internet. It looks like the Opera developers need to go to work on this one.