hello there :D it seems to be some sort of deficiency i,looks like cal-mag def in mid-late stagestry ,try adding some cal-mag to that gorila and if that does not fix most of your leafs ,take a look at this https://www.alchimiaweb.com/blogen/wp-content/uploads/2015/12/KRuFnY4-1022x1024.jpg if anything more you need i will answer in comment section,cheers and good luck !