Not about Orchids but is there a way to stop rot on a leaf?

[Cymbaline]

With so many smart plant people on this forum I thought I would try here. I have this monstera cutting I'm working on rooting. It started developing a black edge.


Anyways I cut of the edge with clean trimmers ( cleaned off with alcohol ) and dusted it with cinnamon . It just continued.

I'm thinking there probably isn't way to stop the edge from dying but I thought I would ask if there is anything I can do at this point or just wait?

Also do you think it is best to let the leaf stay or cut it off?

I've heard two thoughts. A) the leaf provides energy for the plant or B) the plant is using energy to support the leaf instead of focusing on the roots?