It’s a strong claim to suggest no evidence exists. Transgender people commonly claim certain emotions change, with some getting stronger and some smoothing out.

For my part, I had a sharp change two months ago when my estrogen dosage increased and we added progesterone to my routine. (One effect of these meds was to reduce my testosterone levels.) So that was not an aging or maturation related change because it happened in a month. I found it easier to cry and harder to get angry.