your soil has some added stuff to make the pH 6.3 to 6.8 pretty much no matter what you do. most anything you use to fight what they used has a potential for disaster.
just google
ffof buffered.
when you google about the ph in the
ffof soil you might notice the number of threads with these same symptoms your suffering
the consensus seems to be that
ffof might be a bit hot for some young plants of some strains. yes, you will see the back and forth "works on mine" "burns mine", but i tend to go for patterns, and it appears strain related to me. but who knows, it happens often enough with these same symptoms to point me toward this not lights.
lol, if you look at my posts, im all about saying its the light... just not this time. sorry, because the people saying light are much better and much more experienced than i am, even i would always advise listening to Aqua Man and the rest over me... BUT...
see the general "splotchy" appearance? that is what "too hot" soil does, when it is hot, the light does help make it lighter, but it is the soil letting the light burn her. only fix would be to up pot and shake some of that off and use a milder dirt for her till she is a bit older. if you leave her, she will eventually get over it, but she will have issues and sensitivities throughout life.
but, just my opinion, again, i would listen to Aqua Man not me