Most of it's developers and advocates have moved on to other more popular languages is arguably true (in addition to JS/TS I see a lot of Perl devs moving to Go). I know I personally do very little Perl despite working on a team where a significant portion of the work is done in Perl that is less than 2 years old.

But that's not what you claimed, you claimed the developers and advocates were mostly retiring. And that simply doesn't appear to be true ... yet. Give it 10-20 years and I'll expect it to be very true.

I'd also say that Perl's popularity is effectively gone in the general use of the term. While some new development is actually being done in Perl, IME the only people choosing it are already Perl advocates.