How was the plant affected by whatever it is?
Looks like fungal disesease to me. I have seen fusarium wilt in a pepper plant and it looked about the same.
I found it for sale still on planet natural and AmazonIt's my understanding that verticillium wilt does indeed sometimes find a home in cannabis, and if my memory is correct, while fusarium wilt can be arrested or suppressed to some degree, verticillium wilt can amount to the black plague of death.
Can't recall for certain though. I wish my mind worked better these days.
Fungal infestations can make spider mites, etc., look like welcome dinner guests, in my experience, and as the OP said, can and will travel from moms to cuttings. The generational curse of contamination in welcoming soils.
If in a shared soil/room, the OP (or others) may want to research a product called 'Mycostop,' if it's still made/available/approved for use.
Went through my collection of 'approved' pest and fungal artillery last evening, and that was the only one that treated an impressively broad array of serious fungal nastiness. And the bad news was that I'm down to a partial packet that initially weighed very little; a little goes a fair distance with it, though.
Last order of the stuff came from Planet Natural, perhaps about 3 years ago, though if it's still out there and available, I'd guess any serious horticultural store has it on-hand or available.
You might also search for effective alternative products that have the same active critter in them. (*I'd check the spelling, etc., of the organism/critter in the stuff, but I'm being lazy and a bit in pain).
(*Don't snort it...) ;^>)
And we're all feminists, now...in that we treat our females better than we treat males...I view my plants literally as my children and I didn't want new kids being brought up in a hostile environment.
And we're all feminists, now...in that we treat our females better than we treat males...