So, I have a backup installer with PL that is 2.12 or something like that. I installed it in hopes that I just download some 5-10 gigs of updates but now I have to download almost 85 gigs? That's like a whole ass game, isn't it? Why?

It's been like that for years.
https://www.gog.com/forum/cyberpunk_2077/downling_67_gb_again_could_we_please_get_some_clarity

You can patch the main game (for a time, so long all the patches are listed), but you will need to download the complete installers for the Phantom Liberty expansion every time.

This is - among oher reasons - why I skip a few versions between updating, unless I have a specific issue.

Thanks for claryfication.

For the main game if one skips enough versions it's always been the case that patches won't be available, yeah, however what's new is that the Phantom Liberty installers get entirely updated for each minor update and unlike the main game there's no diff patch installer, so you have to download the entire ~38GB worth of installers each time a new update is released.

Reading there's a new update coming for AMD FSR 4 and the same thing will occur unless CDPR would add a diff patch installer to the DLC.

I do hope they reconsider this approach.

Edit: can't recall if they also updated the entire TW3 expansion offline installers for each main game update, too, Though at least with those they were both only between 4-8GB.