I put my phone in my pocket unlocked and when I took it out again it had opened Notes, deleted my growing task list and made a new empty note.
I opened Notes on my Mac, and saw the note in question, yay! ...and then sync kicked in and deleted it.
Guides suggest looking in the Deleted Notes folder, but I don't have one of those on any of my platforms.
Can anyone offer a reason this might be happening?
~/Library/Group Containers/group.com.apple.notes/
[I've never seen a deleted notes folder.]