The leaves are a little light in color, maybe bump em with a little nitrogen. As long as those leaves are old bottom fan leaves I wouldn't worry too much, it's pretty normal to lose the oldest leaves as the plant ages.
Me thinks critters for sure and she is stealing nutes from lowers. Might help to toss a few whole plant pics down but to help we need more info. What kind of soil? What are you feeding her? Veg or flower? Do you use cal-mag?
She looks hungry for N but prolly needs proper ratios of NPK plus cal-mag since they work in tandem