Where does “запуга́ть” come from?

запуга́ть (Russian) comes from Russian за́-, from Proto-Slavic za- — for.

Ancestry of “запуга́ть”, step by step

Step	Language	Word	Meaning
1	Russian	за́-	—
2	Proto-Slavic	za-	for

запуга́ть — Etymology, Origin & Word History | Etymology Explorer