weird artifacts appears in all of sudden

so the model is fine i did baking , unwrapping and a bit of materials in it, and i let you to know this thing happenes everytime sometimes after couple of mintues ,sometimes when i initially open my project 
it is really hard to explain the artifacts that i am seeing so i leave you with these pictures , i can't find the reason nor the solution , undo dosent fix it , the only soultion was loading back into my previous save file
anyone else experienced the same issue ? or do you have any solution or even the reason why this happens
my pc isnt that powerful but i checked the task manager and everything including the ram and cpu are in their 50% of usage so i dont think it's a problem with my requirements , thanks for reading 
my version is 7.1.1  2021 
platform is windows