Strange flashing issue in path traced rendering


See this:

Its a path traced render with high settings & motion blur.
32 samples per pixel per frame, 60 samples, 20 motion blur.

I had to deactivate sampling & caching in path traced render settings since it caused much more of this flashing. Also if i tried to use adaptive sampling it gave me this flashing all over the place.

But now this one corner still has the bad flashing.
What can be done? Do you want to check out the scene?

I think it is a bloom effect that flashes for some reason…

If Nvidia people have time I am happy to send this scene to investigation!