What is going on with Steam updates?

So, over the last day or so I’ve had dozens of reasonably high profile games proc updates on Steam. The vast majority of these games have ended up downloading 0 byte, 512 byte, or 67.5 MB updates. That is really fucking weird and makes me suspicious of an ARG but I am not seeing anyone else reporting this. Thoughts?

Titles include:
Project Zomboid - 0 bytes
Owlboy - 67.5 MB
Road Redemption: 67.5 MB
Broforce - 0 bytes
State of Decay - 0 bytes
ACIV: Black Flag - 67.5 MB
Subnautica - 0 bytes
Age of Mythology Extended Edition - 67.5 MB
GTA V - 0 bytes
Dying Light - 0 bytes
Torment: Tides of Numenera - 512 bytes
A Story About My Uncle - 67.5 MB
The Long Dark - 0 bytes
Divinity Original Sin Enhanced Edition - 512 bytes
Fallout 4 - 0 bytes
Prey - 512 bytes
Grim Dawn - 0 bytes
Transistor - 0 bytes
Viscera Cleanup Detail - 67.5 MB
MGS V: The Phantom Pain - 0 bytes
Rise of the Tomb Raider - 0 bytes
Dishonored 2 - 0 bytes
XCOM 2 - 67.5 MB
The Witness - 512 bytes
Mad Max - 0 bytes
Metro Last Light Redux - 0 bytes
Endless Legend - 67.5 MB
Keep Talking and Nobody Explodes - 0 bytes
DOOM (2016) - 512 bytes
ARMA III - 67.5 MB
Warhammer Vermintide - 67.5 MB
The Age of Decadence - 0 bytes
Darkest Dungeon - 0 bytes
Submerged - 67.5 MB
MGS V: Ground Zeroes - 512 bytes
War for the Overlord - 67.5 MB
Invisible Inc - 512 bytes
Total War Warhammer - 0 bytes
Danganronpa 2 - 0 bytes
The Turing Test - 0 bytes

Hmm. Just found this: https://www.reddit.com/r/Steam/comments/7ewov0/random_512kb_updates_for_several_titles/

Might just be mundane then.

Thanks for that. I was wondering too.

Thanks, I was worried when I saw the Witcher 3 update and thought it would break my mod install again.

Usually, it happens when Steam decides to distribute a visual C update, and the games then proceed to redownload all the content of their _common_redist folders.

Happened to 4 games here, all on the PC, none on the Mac, and sure enough, all those had their common_redist folders brought back from the void.

Good to know!