Ciujbauanswered grow question 4 years ago If its just the bottom part it's from poor ventilation / fans for air movement , I have same thing , some leaves are just falling off when I touch or randomly see one or two drying out .
My advice is not to panic , if its just few leaves , and yours looks like new growth leaves , as long as main top colas are fine , don't try to "fix" something that is just new leaves being weak