P2 proxy repository authentication credentials can incorrectly replace global HTTP proxy server credentials

Problem as follows:

My Global Nexus Security Configuration:

While having the Default HTTP Proxy Authentication enabled
(Administration -> Server -> Section Default HTTP Proxy Settings -> Subsection Authentication) we use a technical user to authenticate at our company proxy HTTP server.

My remote P2 Proxy repository configuration:

If we connect an external P2 Proxy repository (from our customer) to our Nexus installation and configure a proxy authentication for this remote-repository (Section: Remote repository access > Checkbox: Authentication enabled -> User credentials for remote proxy repo setup), the server seems to take this remote repository authentication credentials from the remote proxy repository in order to authenticate at our local HTTP-Proxy which - of course - is not working.

Thanks in advance,
Eric