Where does “múltból” come from?

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

Ancestry of “múltból”, step by step

Step	Language	Word	Meaning
1	Hungarian	múlt	third-person singular indicative past indefinite...
2	Hungarian	-t	Used to form the accusative case; -ed, -t. Used...
3	Proto-Uralic	-tt	—