I just updated, all menus are back. In my case, they seem just a tad bit slower than usual, but no flickering whatsoever. One less thing to worry about.

Just wanted to confirm. Actually, on all three versions since the problem started, turning Hardware Acceleration solves the situation. Basically, no changes in the most recent version. Unfortunately, turning that on is not an option for all of us. Thanks for replying.

@metarhyme What did? Hardware acceleration or version 71.0.3770.271?

This has been broadly discussed here along with other broken features: https://forums.opera.com/topic/43542/latest-update-broke-the-opera-ui

I for one downgraded to version 70.0.3728.95 and marked the package to be hold until fixed.

Given I don't expect the fastest of resolutions, I went ahead and downgraded to 70.0.3728.95 (available here) and I got all pop-up menus back.

For those that hardware acceleration is not an option, this is the alternative for now, I guess. Hope this helps.

Just for the kicks, stable version 71.0.3770.198 doesn't solve the situation, still having all popup menus hidden to the naked eye, but the mouse can click on them and trigger actions.

Ok, so, I am also without O menu and context menus. I recorded a very short clip showing that on Vivaldi and Opera the first option of the context menu of a link is in both "Open link in a new tab" but it is not visible only in Opera (but got lazy and didn't upload it elsewhere to link it here).

Hardware acceleration makes no difference since I don't have a proper video card, it's much better to load work on a core on either of the Xeon processors in my setup.

Some stuff about my system:

I post mostly to be informed when this is fixed and someone reports it here Thanks in advance!