Is this not one of the weirdest dependency issues you've ever seen while running updates? I could use some help, please. It only happens when trying to run paru or yay, but not sudo pacman -Syu

No you are missing all the Cachy repos.

I do not know if you should have v3 or v4 or …

But you have no Cachy repo.

Please see the rest of that other thread for example.