This is a simple firefox extension to hide chess.com ratings while you play.
Lichess has a "hide all ratings" option built into it, I find it a massively useful option, but Chess.com doesn't yet support this mode (although Zen mode helps, I want no ratings).
Essentially all this does is inject a new stylesheet to set text blur on all the ratings I can find.
Stylesheet rules taken from hiagolcm's hide-chess-rating chrome extension.