Where does “неразборчивый” come from?

неразборчивый (Russian) comes from Russian разбо́рчивый, from Russian разбор, from Proto-Slavic *orzborъ.

Ancestry of “неразборчивый”, step by step

Step	Language	Word	Meaning
1	Russian	разбо́рчивый	—
2	Russian	разбор	analysis, review, critique, investigation,...
3	Proto-Slavic	*orzborъ	—