No output that meets expectations.

[Lydanne]

contenthub-1 on  dev is 📦 v0.14.1-dev.43 via ⬢ v22.15.0 
➜ envsubst --version
envsubst (GNU gettext-runtime) 0.25
Copyright (C) 2003-2025 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
Written by Bruno Haible.

contenthub-1 on  dev is 📦 v0.14.1-dev.43 via ⬢ v22.15.0 
➜ echo 'welcome ${USER:=312}' | envsubst
welcome ${USER:=312}