For those curious, Proton is included with Steam, but GE's Proton includes many tweaks, improvements, and yes, rebasing on the latest upstream versions of many packages. For many games running in Linux GE Proton tends to be better than Valve's default Proton. GE Proton also includes features earlier than Valve, like FSR3 -> FSR4 upgrading, etc.

CachyOS makes also makes a Proton that's similar but different from GE's. There's also Valve's Proton betas, Proton Experimental (which is often updated within days of major releases).

ProtonDB.com is a great resource for finding out which "Proton" works best for a given game.