Notes app: "You have changes that can't be uploaded"

Hi all:

Every single time I open Notes on any of my devices I am given the following notification: "You have changes that can't be uploaded. / Changes you made to '[Note name]' can't be uploaded since the owner's iCloud storage is full. Your changes are saved on this device and will be uploaded once the owner creates space."

A couple of things:

1. I do not recognize the note in question—it sounds like a grocery list that a roommate might have shared with me years ago, but I cannot find any trace of it on either of my devices/in my messages/on my iCloud. It simply does not exist. But it does.
2. My own storage is far from full. Dozens of gigabytes separate me from a Notes file breaking the camel's back.
3. None of the folks I have contacted have found a similar Note on any of their devices. It seems like it was deleted a while back, but the record of it having been shared with me has left it trapped in some kind of limbo.
4. I've put up with this for months, but it's really, really frustrating. I cannot use my Notes app for long because that notification appears repeatedly. Like, 4–5 times over the course of composing a single grocery list. I like Notes for its ease of use, generally: I can access one file across my devices. This is putting considerable wear on that perk.

Has anyone else experienced something similar? What should I do, apart from breaking the thing in half, I mean?

Thanks in advance