Someone can HELP with this problem?

The odd leaf being cannibalised with age is nothing to worry about if not many show similar signs. older fan leaves do give themselves up to emptying their chlorophyll stores and killing the need to supply them Thisbcan be a natural process related to which leaves benefit and which have outlived their intended purpose, bit like dead skin cells shedding . If you are using l.e.d rhen it would be advisable to prepare for mg deficiencies as led leeches it from the plants, coco does similar too , so it may be a good standby for any rust spots appearing in busy leaves.