Custom tags in the search field

Why are custom tags not included in the 'Tags' option in the search field of MacOS Finder? Is there a way to fix that?

I have a tag '5' to mean 5-stars and entering 5 in search does not give me an option to pick Tags 5 instead of filename like it does for 'Blue' (or any built-in tag).

I can use 5 in the Tags area in Finder left-pane but that always searches the entire computer.

Thanks!