Another Ventura filesystem bug. There is a post with a workaround:
but I am pursuing with Apple to get it fixed. I can copy/move single files from iCloud folders, such as desktop, but folder copies fail with the error below. Apple Support says that they have had multiple reports of the problem. Issue has been referred to development.

For the sake of completeness, in case anyone ever finds this thread: in the end I simply recycled the iCloud Drive switch in settings: turn it off, turn it on again, wait until everything has resynced. Took a while, but now it is working just fine.
but I am pursuing with Apple to get it fixed. I can copy/move single files from iCloud folders, such as desktop, but folder copies fail with the error below. Apple Support says that they have had multiple reports of the problem. Issue has been referred to development.
