Newly installed games will download and install dependencies when launched the first time if they are needed. I have also seen this after major updates.

I have never seen it just randomly happen when launching an installed game that has not been updated.

引用自 AmsterdamHeavy：

Newly installed games will download and install dependencies when launched the first time if they are needed. I have also seen this after major updates.

I have never seen it just randomly happen when launching an installed game that has not been updated.

they are deffo not new, they have been on my PC for a long time, and I played them daily, and there wasn't even any patch for them recently.

It could be shaders that get updated regularly. There is an option to use shaders in the client.

I'm starting to have it happen launching Mafia 3 or Vermintide 2.
Pressing "No" in the UAC prompt will make the game launch as normal, thankfully. Choosing "yes" will prevent the game from launching as it will get stuck on "running install scripts" for DirectX and similar runtimes when it doesn't need to do this anymore outside of first launch.

Very strange behavior. Hopefully it can be fixed as I instinctually press "yes" in these UAC prompts all the time.