m0useanswered grow question 7 months ago Its beginning on upper growth and from the base of the leaf outward.
Its reminiscent of PH fluctuations to me but could also be something bad in the root zone like a fungus or bacteria.
Hard to say, I don't see much, if any perlite in the mediums mix to give good drainage and oxygenate the roots. Making me think its more of a root issue,
Test your mediums PH in the pot via runoff or slurry test. curious if is on point.
Good Luck!