Since I got a new computer, I'm getting the following message all the time:

The document could not be autosaved. You don't have permission.

This means my documents aren't being autosaved for some reason. But it gets worse. When I try to save a document, a lot of the time I get the following message:

The document “[documentname]” could not be saved. The file is locked. Do you want to save your changes to it anyway?

If I click on “Save anyway”, I get the following message:

You don't have permission to save the file “[documentname]” in the folder “[foldername]”. To view or change permissions, select the item in the Finder and choose File > Get Info.

I have all of my personal documents on custom folders in my iCloud Drive. All of my folders and the documents therein have permissions set up such that I can read and write. (The answers here and here are therefore useless to me.)

I've also checked the permissions of ~/Library/”Autosave Information”, and I can read and write there as well.

I didn't have this problem with the same files on my old computer. I migrated everything to my new computer with Time Machine, which shouldn't mess with permissions, but, as stated above, I've checked my permissions anyway and they're fine.

I don't know whether the problem is a Monterey issue (I had Catalina on my old computer), an Apple-Silicon problem (current computer is M1 Max, previous computer was Intel) or something else.

Please help.