It appears possible to generate cursed system notes
While going over Reference redactor removes links where it shoul... (#584587 - closed), I noticed the following system note:
That's a link to me. I didn't intend or mean to do that, or even notice it at the time.
It turns out it also happens for project references; both UserReferenceFilter and ProjectReferenceFilter cache based on the target object, but not according to whether custom link text is used!
Quick reproducer:
[test](@kivikakk)
@kivikakk
[hmm... where'd the text go?](@kivikakk)
@kivikakk
Renders as:
Screenshot for posterity:
Edited by Asherah Connor

