Any ideas

[growell]

Has anybody got a clue what's happened to these it's happened over night, it's only affected 3 plants of the same strain 1 was a bit worse than the other 2 it happened all over the plant mainly the big leaves it's not a light issue it's not a ph issue or a root issue don't think it's a deficiencies as it's affected the top middle and bottom of plant the only thing I can think of is the plant has used up all it's energy in them leaves to drop them but would it happen all at once. So any ideas guys thanks

[CaptainWiese91]

Looks like a nute burn.
but without any info about setup or pictures of the whole plant/plants. It’s really just a guessing game