Valve has released a new beta patch for Half-Life 2, HL2: Episode One and Half Life 2: Episode Two. This new beta patch adds Vulkan support to the game, meaning that these HL2 games no longer use/feature the DirectX API.
Additionally, this new beta update adds support for ultra-wide monitors. Not only that, but it improves FOV (increases max FOV from 90 to 110), and packs a number of interface improvements. Furthermore, this beta update fixes a number of bugs and issues that the community has reported over the past decade.
Now the bad news here is that this beta update introduces micro-stutters. This is something that Valve will have to look into as these stutters can be annoying. My guess is that the final/public patch will not be plagued by them.
Valve has not released any changelog, but you can find below a video that highlights the changes.