These builds include a small patch which fixes a prefix population error that can happen when first running a game in a new prefix.
Anyone using LinUwUx's original Proton releases may have seen that when running a bare prefix, it doesn't install wines files properly, cause the game to either silently fail, or, throw a Steam API error.
These builds wont do that.
If you're having issues launching a game, start the game with prefix's LINUWUX_DEBUG=1 & PROTON_LOG=1 and make a report with the log output from ~/steam-default.log included.