So i remember the Game had Cloud Save Support but its not here anymore. Also higher Resolution don’t work anymore like it used to be. Does someone has an explanation for that? Also why are the cloud saves reduced to only 200mb?

Regarding the cloud saves there is even a sticky regarding this:
(The short gist of it is - because of strain on storage space it has to be severely reduced.)
https://www.gog.com/forum/general/email_about_cloud_saves_dont_worry_its_from_us

That fact that apparently it has even been entirely removed from some games is surprising though.
Regarding the higher resolution issue though -- I have no idea.

After 1-2 years Soul Reaver had an update on GOG, but then it was rolled back for some reason (and now with the remaster almost here I don't see it getting much support), maybe that could explain the high res issue

I just checked the game on gogdb and I can see an update made to the game very recently - https://www.gogdb.org/product/1207659030#changelog. It says the build was changed at the end of september. Is it possible the game was also part of the Preservation Program ? It does not have its own store page anymore so there is no way to confirm but it does feel like it is possible. What have been changed though is impossible to tell. Also I do indeed see cloud saves on the pcgamingwiki for the GOG version being supported.

Edit: Now that I looked a bit more careful it seems the new build was reverted like Memecchi mentioned. It goes from 1.2 ⇒ 1.2 20230712 and then back to 1.2 20210923 ⇒ 1.2

About the 200 mb limit - I am really surprised you have not seen at least one e-mail being warned about it. I received quite a few before the change!