(defcustom org-tags-match-list-sublevels t
  "...
This variable is semi-obsolete and probably should always be true.  It
is better to limit inheritance to certain tags using the variables
`org-use-tag-inheritance' and `org-tags-exclude-from-inheritance'."

...


"org-tags-match-list-sublevels  +  search +LEVEL>n " is a very useful tip, if you have many sublevels with many different tags,
it can not lost search results nearly, why we will semi-obsolete it?