Help please

Anybody can help me out this leaf suddenly appeared like that all garden is ok no nutrient burn nothing

What are you spraying on them?

I use spray and gro

Its 1 leaf youll be fine. Dont spray them with anything if you need it more humid in the grow room you need another big oscilating fan, after adding one to my grow tent my humidity went up from 17 percent to 45 percent lights on