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.
SMS is famously NOT SAFE and the worst second factor to use - steam already has a REALLY GOOD two factor authentication feature- why not just use that? Force me to do a steam guard challenge? Why sms a code? I already need to do a steam guard check to log into the backend?!?

Sleepy-girl representation is important