According to these new numbers from Valve, the Linux customer base is up to 1.96%, or a 0.52% jump over June! That’s a huge jump with normally just moving 0.1% or so in either direction most months… It’s also near an all-time high on a percentage basis going back to the early days of Steam on Linux when it had around a 2% marketshare but at that time the Steam customer size in absolute numbers was much smaller a decade ago than it is now. So if the percentage numbers are accurate, this is likely the largest in absolute terms that the Linux gaming marketshare has ever been.
Data from Valve: https://store.steampowered.com/hwsurvey/Steam-Hardware-Software-Survey-Welcome-to-Steam?platform=combined
It automatically uses Proton for titles that Valve has whitelisted as compatible. To play anything else you need to check a box in the settings. Honestly, it should probably just be checked by default.
Probaby just to deter non tech savy people to blame all the problems on steam without realising it wasn’t made for linux in first place. There may not be a lot but with how popular steam deck is, I won’t be surprised if a lot of people are trying out linux for the first time.