Valve Bans Forced In-Game Ads From All Steam Titles

I want to add, this was an existing ruling, they just clarified the rule. Every article it seems is using each-others clickbait titles(the linked article even references it in the edit).

The change that they made was that they added a dedicated section to the developer guidelines, where before they only had it on their pricing page.

This rule has been in effect for 5 years now according to steamdb.