I wonder, did you noticed before bug, that one of the mouse gestures failed?
what I mean is, did you tried to perform mouse gesture in fast way or maybe accidentally clicked two times with right click while performing gesture, so that instead of action, context menu fired....
because, on my side, that bug (no gesture, no keyboard input) happens almost every time AFTER I screw something with mouse gesture...
eg. I perform close tab gesture, but I did it too fast or something "else" happens and tab gets closed, but on newly activated tab, context menu breached out (and it shouldn't). After that, gestures and keyboard are bugged
so I'm just guessing, it's probably some chain bug that pulls all other gestures and keyboard input

That´s exactly how the bug appears. Though I cannot "feel" if my mouse gesture was too fast.

because, on my side, that bug (no gesture, no keyboard input) happens almost every time AFTER I screw something with mouse gesture...
eg. I perform close tab gesture, but I did it too fast or something "else" happens and tab gets closed, but on newly activated tab, context menu breached out (and it shouldn't). After that, gestures and keyboard are bugged

so I'm just guessing, it's probably some chain bug that pulls all other gestures and keyboard input

Details? What version of Opera, what version of Windows, and when does it happen? (Aftet a couple of hours, after certain types of content, etc.?)

Thank you for your questions!
It´s not bound to a specific version. So I cannot tell you when it happens, either. And yes, it happens after some time of browsing. But only sometimes. No matter if I cleared the cache.
I´ve installed the uBlock Origin-addon, the Pocket-addon and that´s it.