Root problem

so i recently had a major fungus gnat problem, it seems to be under control now literally see none even have yellow sticky cards down and they are only getting the odd 1 or 2 but the plants are extremely weak looking and barely hold themselves up the plant in the fair back had already fallen over while the infestation was bad, it has prem soil half coco coir in the pots a lot of leaves have fallen off but since I've gotten rid of them the damage has slowed down but now i'm worried about them falling over as the video shows i haven't watered in a 4+ days they still aren't showing signs of under-watering.

should i keep not watering until they wilt is there anything i can do to help the roots? the damage is from the fungus gnats i'm guessing? and the leaf damage. they are about 3-4 weeks in flower as well.

obviously the buds would be starting to get top heavy but the roots must be extremely damaged is there literally anything i can do to make them grow faster to support them? all thoughts and whats actually going on here would be appreciated!

video of plants

Great vid, much better then pics. What I would do is poke 4 holes into each pot, north south east and west. Use some garden tape or soft string to give them some support. Start adding B1 to your water. You might think about picking up some Hydroguard or Aquashield for your roots. Also keep everything clean and lower your temps if you can to 75. Be very careful not to overwatering at this stage.