Hard to tell cuz I don't really see the thing itself. Cutting off the roots are never a very good thing BUT roots are shrinking off if exposed to light so if there's a means to expose excessive roots to light you can use that to reduce their amount
You should probably try a big store such as Herbies for example, those who are there for years and probably wont lose their rep to go unfair
https://herbiesheadshop.com/
It does look like a bit of nitrogen deficiency, not to mention that those leaves don't really look like ganja plant...I wont be risking giving any advise at that point
Uhm you may try running it with something that cleans easy like a blunt run, just to make it easily to clean, other than that - does it take a on-time cartriges?
Big pot for the clone? Clones are not getting that big usually, don't need a huge pot. Huge pot may also not be that good for the roots, I mean too big