YES IT DOES GO AWAY! I had it really badly for ~8 months, moderate for another ~4 months and now i feel ALIVE and so does everything else
in this year long period there even was a 5 month period where i completeley abstained from marijuana and i really started seeing improvement after 3-4 months, even so that i even smoked a bit after
derealization sucks. mj doesn't always cause it, but if it caused you a few times, then you better abstain from it. the second thing you MUST DO is accept it: no it's not 'brain damage', no you're not going crazy or fried your brain etc... there are no medical treatments. then, forget about it.
focus on trying not to get stressed and anxious - it exacerbates it - and move on with your life, which is a tricky part
btw, on my point of view (pseudoscientiphic), derealization is your brain dulling your experience of consciousness because it feels reality/your mind is kinda dangerous, as to avoid/dissociate you from bad feelings/situations. also, in a less pseudoscientiphic manner, i read a few articles on derealization and subjects suffering from it apparently had less emotional response from visual and sensory stimuli - visual hypoemotionality -, less connectivity from the visual to the limbic system.
again i view this as a defense mechanism from bad situations. like a bad trip causes it: your brain sees reality and your own consciousness getting very weird and scary so it dulls it out a little bit.
it'll not go away if you don't accept it and forget about the 'i'm damaged' thoughts, derealzation itself is an issue of not accepting/facing some issue (the situation which left you like that earlier)
well, sorry for the rant but stay positive yes it does go away!!