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Seed or clone starts in a 3x3x3 inch and transplants to a 6x6x8 inch only when rootbound. No transplant shock ever. The plants explode in fresh growth the next day as the roots bite into fresh nutrient rich soil.
I don't usually let them get this tall or grow into the veg lights and burn the top leaf, but I've done them this way for many years and never lost a plant. Cannabis hates having its roots messed with. Not a root knocked out of place and not one grain of soil dropped.
Let that pot get feather light before you water again. Even let the plant wilt a time or two just to show you how badly you're overwatering. Small plants in big pots stay wet for days and grow slow. Big plants in small pots drink fast and can be push hard with frequent feedings. Small plants in huge pots you wait and wait and it is still wet and wait more and.......
I'd put that back in a 3x3x3 in pot and let it get at least 8 inches tall.