Thanks for the report. I can reproduce.
I did some testing.
It seems that of []()
the text within [] is captured in unlinked mention.
the text within [] is captured in linked mention.
This issue is not related to https://forum.obsidian.md/t/same-reference-shows-up-in-both-backlinks-and-unlinked-mentions-for-a-note-which-is-included-using-header/200
which was fixed