Where does “tűnt” come from?

tűnt (Hungarian) comes from Hungarian -t, from Proto-Uralic -tt.

tűnt (Hungarian): third-person singular indicative past indefinite...

Definitions

Step	Language	Word	Meaning
1	Hungarian	-t	Used to form the accusative case; -ed, -t. Used...
2	Proto-Uralic	-tt	—