i really dont know whats happening , i am just using immersive portals + pehkui + optfine and these things are communly happening now , these weird visual glitches , i really dont know if is because of compatibility issues with optifine but this is happening

Try getting rid of Optifine to see if it fixes the issue cause it is the likely cause if I read correctly I think Optifine does not like Immersive Portals at all.

Does this happen when render regions is turned off?

Does this happen when render regions is turned off?

yes , thanks , now i can play the game without having a seizure ,and yes when its off this happens