If they take hold they are almost impossible to get rid of.
2 types of white fly ,sounds like you got the small ones which are the bad guys, if the room is warm they multiply by the thousand every few days .
Like gnats they dont affect the final weight too much just very annoying .
As said...
To do that it was hotter than 38 , i think it was closer to 45 with hot strong winds in most of AUS this week and this will give them minor to major heat stress. Some strains handle it better than others and the more hardened off they are with previous hot days the quicker they will bounce back...
There is nothing wrong with this seedling. Dont change anything and dont put a dome over it at night.
As long as the new growth is healthy you have nothing to worry about.
To prevent mold and rot with the clones only use a dome for the first 24-48 hrs. If you remove the dome and they collapse then your cloning technique is fucked. Always use large stem cuttings from a healthy mother.
Also that medium is horrible, what is it? it looks like quarry sand and you need...
It looks like the medium is causing the ph to be out. Use a different medium eg coco to re pot and do it soon. Feed it veg hydro nutes every watering starting at about 25% strength.
Im not sure what is uglier the plant or your foot.
Its nute burned (the plant) due to a medium not suited for cannabis growing and /or overfeeding and there is not much you can do now to fix it. Drop the nutes back at least 25%.
The causes for early leaf drop could be too much feed ,reduce by 20- 30%, veg and flowering.
Also the pots being too small, drying out too much too often can also cause the plant to yellow and drop leaves too early, the salt build up stops the uptake of N.
Its some sort of bug that sucks the guts out of the leaves rendering them useless, eg white fly. Its not grubs or caterpillars. They probably weren't hard enough to go outside.