Games in D3DMetal mode, such as Forza Horizon 6, start with a PlayStation controller connected. Before a launch Steam can show a short notice, and with a DualSense or DualShock connected it asks whether to use Steam Input for it. Steam cannot draw its own window in D3DMetal mode, so that question stayed invisible and the game never started. Steam's log showed it waiting at "ShowInterstitials" on every Play. Highball already recorded the "controller recommended" notice as seen before a D3DMetal launch, and now records every pre-launch notice Steam can remember, the same way Steam does when you dismiss one. A "don't show again" you ticked stays as it is. Thanks to the player on Discord who sent a video and Steam's own log, which showed exactly where it stopped.
When the database changes a game's fix, an environment set up before now follows it on the next Play. Fix settings used to be written once, when the fix was applied, so a corrected fix never reached the people who needed it. Planet Coaster 2's fix, for example, dropped two Metal settings that froze two Macs, and environments that already had them now lose them.