Creating Collaborative Space Protected as Standard?

Hello,
do you know if I can create new CS with visibility Protected and family Standard? On Cloud R2021x...

I tried it and I'm not able to create it... If I have Protected it is possible only as family Design...
But I didn't find in documentation or anywhere anything about this limitations or any reasons why it is like this?

Please do you know anything else or more details about this?

Thank you.