Cannot see some programming.dev communities

I'd like to join the !cpp@programming.dev community, but I can't find a way to do it:

• I can't find it in the community list of lemmy.one.
• This link gives a 404: https://lemmy.one/c/cpp@programming.dev

These links are valid though:

• https://lemmy.one/c/programming@programming.dev
• https://programming.dev/c/cpp

Is this normal?