Valve will now require Steam developers to use SMS verification. Starting Tuesday, October 24, developers will need a phone number associated with their account before publishing new versions of their game or adding new users to the account.
"As part of a security update," wrote Valve, "any Steamworks account setting builds live on the default/public branch of a released app will need to have a phone number associated with their account, so that Steam can text you a confirmation code before continuing.
"This change will go live on October 24, 2023, so be sure to add a phone number to your account now."
Read the full story over at Game Developer.
I foresee this becoming quite ridiculous for companies that have multiple concurrent releases being set live by different production groups, for example.
Or just an absolute pain if they really are going to extend it to everything Steamworks down the line.