Where does “Ковалёв” come from?

Ковалёв (Russian) comes from Russian -ёв, from Proto-Slavic *-evъ.

Ancestry of “Ковалёв”, step by step

Step	Language	Word	Meaning
1	Russian	-ёв	Alternative form of -ев
2	Proto-Slavic	*-evъ	—

Ковалёв — Etymology, Origin & Word History | Etymology Explorer