Had similar spotting on my @FastBuds too! I'm thinking rust fungus or leaf sep. form watering/soil or a Cal/Mag deficiency.
I clipped all my leaves with spots and did a disinfect of the grow space in case it was fungus and added a bit more Cal/Mag in with my feed.
Been keeping an eye but not spreading around much and hasn't shown up on new growth. 🙌
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