@freemo Yes, the code was from Glitch-Social, and made available for plain Mastodon by Renato Lond's work on his own instance.
Quoting one of my own posts :
"** We thank Renato Lond, the admin from https://masto.donte.com.br/ for porting the code from GlitchSoc and creating a Mastodon version, which he added to the main project Git.
Renato pointed me to https://github.com/tootsuite/mastodon/pull/8427 for the code in question. "