The pattern flashes every time right after I pass through the grid. Is there a way to fix this? This is an EVEE render; I suspect this is somehow related to transparent node and I tried to change Bloom and other rendering settings, the issue seems to continue even in Cycles.
It’s very hard to troubleshoot something like that with just screenshots. You could upload the file for us to take a look and see if we can help. One solution that comes to my mind is to remove or tweak the troublesome frame.