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…

Google Pixel not being a dumpster fire of a smartphone challenge: impossible

“Folks, it’s a feature.” -some Google employee maybe-

Google will always say “bah humbug” and move on as though nothing happened.