It looks like that sub was completely removed recently but the DB::Color module hasn't been updated since 2015.
Edit: of course that was in bleed so that specific change is probably not exactly your problem unless you're using a bleed compiled perl. That being said though looking in the 5.34.0 source I don't see a sub _cmd_l defined therein.
Oh and the sub looks to maybe have been renamed _cmd_l_main (haven't grobbled through the entire history, but as a guess . . .). Prossibly if you patch DB::Color to use that instead of the plain _cmd_l it may just work (in which case you probably should file an issue with the author through the github tracker).
The cake is a lie.
The cake is a lie.
The cake is a lie.