What is the version of mpg123 in release 15.0.37.9? Can now use HTTPS?

The version of mpg123 is 1.32.10 or newer to utilize HTTPS streaming capabilities. Is it part of the FreePBX release?

Probably not.

FreePBX 15 went GA about 5 years ago and goes EOL on September 1st, 2025 per links in FreePBX Versions topic.