I'm on an iPhone 12 mini and it happens once there are 50+ tabs open but it seems to be self-healing at some stage. The blur kicks in too late but when trying more often it kicks in just at the right moment.
I'm not really helpful right now to reproduce. Overall, Safari seems far more advanced in switching the screen.
What I see on Orion is that my home screen shows up as well as my opened tabs, not sure why this is happening at all when rotating the screen.