I believe this is a major reason. Demographic shift.

Perl grew to prominence when being a creole of C, shell, sed, awk, and lisp was an advantage. Anyone who might reasonably use it would be familiar with at least a few of these tools.

Now, we live in a very different world. JavaScript is the new BASIC. Everyone has JsBASIC installed on their (virtual) machines. So that's what people learn on their own. Python and Java are closer to JS so, the transition is easier (at least superficially--I could argue that JS and Perl a lot in common, designwise).