Unenthused (adjective)
Not enthused.
Unenthusiastic (adjective)
Without enthusiasm; unexcited.
Wiktionary
Unenthused (adjective)
not interested or appreciative; unenthusiastic
“they are pretty unenthused about the idea”
Unenthusiastic (adjective)
not having or showing enthusiasm
“an unenthusiastic response”
Oxford Dictionary