iCloud Drive won't sync, stuck on "Uploading X items"

I've been having difficulties getting iCloud Drive to sync normally after updating my MacBook Air (M3) to macOS 26. Whenever I add a file to my desktop folder, for example, which is part of my iCloud Drive, the syncing process starts but never ends. If I click the iCloud sync status icon on Finder, I get a message that says "Uploading 1 item" (or more, depending on how many files I added) and the progress bar won't move past a certain point.

If I reboot my MacBook, the syncing process works normally for maybe a couple of hours, but then it stops again. Right now, for example, it says "Uploading 5 items", but nothing happens. I tried rebooting my modem, but that didn't help; I also tried turning iCloud Drive off and on again, as suggested by some users, and that seemed to help at first, but the problem came back.

Anyone else experiencing the same?

[Quick edit, just wanted to emphasize that this issue wasn't present in Sequoia, and it also doesn't seem to affect either my iPhone or my iPad, which are both running iOS 26.]