Anyone see something like this before?

[miyagi]

Yea I personally have seen this happen to new vegetation from spraying fulvic acid, even in smaller amounts. Just my .02. I have also had broad/russet mites. Those things will typically go for clones/weaker genetics. Healthy new seeds you will see be able to fight russets off mostly, or like they aren’t attracted to them as much. Under the leaf crevices and in the kinks of the leaves. They are tiny as shit. Nothing kills them aside from the infamous guardian spray that has been banned.