You 100% won't. I already went through all this before replying to the original question. With my 'dots' problem (GT7 PS5 version), I deleted the game and its saves from my PS5. I then reinstalled the game and all my cars were still there. The only way I could get a 'clean' new game, starting again from the beginning, was to create a new PSN profile and launch the game on that. Neither the reinstall nor the new save data had any effect when it came to curing the 'dots' - they were still there.
TBH I've now reinstalled the game 3 times and the 'dots' still appear on my cars (GT7 PS5 version) when I paint them in the livery editor.
Regarding the flickering, try googling it. There are some notes about the screen settings for your PS4 which might help. However, I still think it's a GPU issue and no amount of reinstalling the game will help. It'll just waste hours of your time for nothing. By all means try it if you don't think I'm right.
I didn't want to believe there was a fundamental problem with my PS5 regarding the dots, but no one else has this same issue - just me. And as I said, the PS4 version of GT7 runs fine, no flickering at all, on my PS4 console.