Well, 8 inches & straight leaves makes me think it could be sagittarius. If so it's kinda pale. Do you use ferts, either root tabs or water column 1s? How long are your lights on? Your rotala behind the sag? looks a bit pale too. So maybe a bit more ferts & a bit less light. Go slow with changes. I do 6-8 hours of medium/lowish light for those plants but it depends on your tank's depth too.
I think I see the beginning of black beard algae on the left most longest sag leaf & maybe a couple coming from the big center clump. Just pinch out those leaves close to the base, bba often occurs on old leaves.