Looks like (old) leaf tip irritation. When fans blow the leaves around, the leaves can rub against each other, which will irritate 'sores' in themselves and the other leaves. Not much can be done about it.
Can also happen if you 'crush' a portion of the leaf. Like picking-up the pot and trapping a piece of the leaf between your finger and the pot.

The lower leaf with brown edges is likely from hanging too close (touching) the medium.

Old leaves are old news, but your newer growth looks pretty good.