Odd spot on leaf!? Prob or no? x.x (1st time grower, as if I need say lol)

hello everyone

on one of the clones that has been having the hardest time with everything going on. I spotted, this spot on the one leaf. no others, as of yet. (hope no more will pop.) I looked around for bugs and no see anything. Can this be normal for a healing plant? Once the leaf turn yellow, can it go back to green or will that part slowly die off and will the rest of the leaf go too x.x

I am sure they are a little stunted too. Will extra grow week or two help get them going again?


Well here is the spot. How she look?
 
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