Man pages matching name envsubst in section 1:

envsubst.1.en	debian 10 / gettext-base
envsubst.1.en	debian 11 / gettext-base
envsubst.1.en	debian 12 / gettext-base
envsubst.1.de	debian 12 / manpages-de
envsubst.1.fr	debian 12 / manpages-fr