How to set right on protected branch with allow to push

Hi community,
I’m using Gitlab version 13.11.4 on premise with docker ( the official omnibus image).
I have strange behaviour using the ‘Allow to push’ on protected branch.
Maybe I misconfigured some option.

My case is the following:

  • I chose to configure the option : “No one” on protected branch.
  • When I add in addition to No one a a deploy key that is allow to push in addition to the first one, The No one is not working anymore.
    What I mean is Maintainer and Developper are allowed to push.

I’m wondering if it’s a bug or a standard behaviour ?

Thanks in advance for your response and suggestion.