That's what I figure, too. I reckon they may have optimized the game to run on a newer version of unity perhaps. Steamdb says that all the new update files are of differing file sizes, some bigger some smaller, so I think it was an overall optimization/polish update? It was insane cause i literally installed the game 5 minutes before they updated all the library artwork, and then I had to download a patch. I was like "woah, the timing.."

I recently bought it with plans to play it now in the summer and I was surprised to see it got updated

14.3 GB disk writes, hope it's a huge content update

This is new build based on version for PS5/ XBOX,
No info about new content but is possibile they take care about few bugs.
I check menu and see dynamic resolution option, but now I not remember if was previously present.

"A new update has been released for Blacksad: Under the Skin!

Here is what it brings:
Updated Unity engine version (together with consoles)
Graphical improvements:
Fixed the shadow artifacts
Increased the shadow quality

Updated splash screen to use new image
Fixed a bunch of broken shaders
Fixed Infinite loading when changing focus during loading screens
Adjustments to Cloth physics"

Wow, that cool! I am palying/enjoying this game right now!
Noticed the cover image change, got the update.

i got this game as soon as it came out and completed it without any hick ups bugs or crashes . After a few patches were released lots of users reported that the game was bug ridden and unplayable so i dont know what they messed up.

That said ... even though i completed it i must have missed a lot out as it says i only got 19 of the 39 achievements

It's odd. Blacksad had been parked in my library, and I was determined to finish one game before I bought another on the summer sale. Blacksad was already top of my list for games I haven't played yet, and here it comes with a new shiny 8gb coat of paint.

Hell yeah I'm in! The vibe is most excellent, and it's playing like late-night jazz .
(with fists)

Is it possible to skip or delay update on Steam Decm? I have limited data plan and away from wifi for several weeks

Yes, go to library, click right on the game, properties, update, click ticker to scroll down to what you desire, top right, hope it helps, couldn't use quote for some reason :)