Veroni

Yeah, I think it might be lack of nutrients. My bird of paradise plant made two crumbled leaves like that after being in the same pot without fertilizer for a long time, and leaves look fine again after I repotted to new soil.

I read [1] that bananas need fertilizer with a 3-1-6 ratio, for example 6-2-12. They need a lot a K2O (potash dioxide). I thought that helpful, although the authors seem to regard only balbisiana and acuminata.

[1] "Banana Growing in the Florida Home Landscape", Crane et al, University of Florida: Banana Growing in the Florida Home Landscape