How to make a check to look for all letters in the text with lower case in regex?

Question

Regular Expressions

I can have a different value and everything with a small letter was replaced by ##. And the big ones were replaced by ####.
Here is an example https://regex101.com/r/Wlvakr/1
Let's say there is dmY It
was about fantasy to do /(\w+[az])/. But I realized that it does not work. I can take all the letters, but in a small register it somehow doesn’t work out well for me.

Answer 1

https://regex101.com/r/Wlvakr/3