Guess I'll be buying this on steam then. Congrats!
Valve has known for 2 and a half years that the Steam client began causing harm to users with several medical conditions after an update. They refused to roll back the update, have blocked safe workarounds for affected users, and support has told some customers asking for help with the problem to hurt themselves. Also since the issue began, but separately, they've committed multiple violations of privacy laws in several European countries and NZ and Aus (I know they've been reported to relevant authorities for it in at least 3 countries).
I'd strongly recommend buying here and getting a Steam key rather than buying direct from Valve and giving them any money for it.
EDIT: In case you need a source, here's a discussion of the problem that dates back to late November 2019, first reports were a few days after the update, which was the end of Oct.
https://steamcommunity.com/groups/SteamClientBeta/discussions/3/1658943116231004...