The bumps appear to be coming from the little metal tensioning tabs pressing against the back of the screen through the copper heat transfer tape a little too hard.
https://youtu.be/xEBYVJ2_r_Q?t=103
https://youtu.be/0poyvpB7Fkw?t=193
iPhone 15 has these tabs but only on the reinforced edges of the frame and Samsung doesn’t use them at all for Galaxy S series
Bizarre design choice from Google to have the tabs press directly into the back of the screen…
P3, P5, P7 are all on one side of the CPU, so it’s likely the cooler pressure on the CPU IHS isn’t even for some reason.
Some ideas:
Use more paste and make sure the paste imprint is even.
Double check to make sure you didn’t mix the LGA1200/1700 standoffs which are different lengths.
Make sure the excessively large universal Arctic mounting frame isn’t catching on a VRM component.
Make sure the contact frame tension is even across all four screws