i typically would only use GET /v1/taxa to return detailed information about a taxon, or to search by id or relationships, not to search by name. to search by name, i would probably use https://api.inaturalist.org/v1/search?q=velutina%20velutina&sources=taxa or GET /v1/taxa/autocomplete.
i doubt there’s anything the staff would consider a bug here, and to the extent that anyone would want to change the behavior here, i think that may already covered in the broad feature request here: https://forum.inaturalist.org/t/search-for-and-highlight-only-exact-matches/670
just based on what i’ve observed anecdotally, the rate limits generally seem to be the same across endpoints on all iNat APIs, although autocomplete ones seem to have slightly higher limits, and map tile ones seem to have high limits, too.