This is what the memory usage graph looks like:

@alobpreis
This mainly happened when I drew some shapes on a numerical map at work. Nothing special was happening with the memory. The graph line was flat.
I'm trying to reproduce the situation today, but the error won't pop up.

And Opera's task manager, done now:

Same problem here.
This is a company computer. After updating Opera to version 90.0.4480.54 today, it happens every few minutes. It is impossible to work.

And it's not a matter of lack of memory: