Hi Florian,pretty much looks like some issues in your on premise S/4HANA 2020 settings. As you haven't shared what you've done so far, I recommend that you check your whitelisting or uconcockpit and if the exposure_system_aliases_mode is set.Best Reg...
I found some documentation regarding the security concepts which might help you answering your question: SAP Cloud Platform Security Concepts and a learning page from SAP Cloud Platform Security team.