The Beta update makes several small but important changes to Half-Life 2, most of which seem geared toward making the game run and look as good as it possibly can on Valve's upcoming Steam Deck handheld PC. That changed recently, with the unannounced release of a new Beta update branch for Half-Life 2. The company might fix the occasional bug if its developers (who seem to work on whatever they please) feel like it, but that's about it.
What just happened? Valve, and most other game developers, typically don't give much attention to its legacy titles, like Left 4 Dead, Portal, and the Half-Life series (barring Alyx).
