Oh, I see now. I'll try this. Thank you a lot!

No, I tried to use my NEFilterManger for the SimpleTunnel project Content Filter and it works properly, however, I can't make it work in my project on SwiftUI.

Thank you! I'll look more into this.

I also tried to separate Core Data module in empty project without Network Extension and added some basic crud in Content View (displaying list of rules, adding/removing rules, etc.) and it works well. However, if I run my main project with Content Filter and DNSProxy I receive that message in console and in System Settings only DNSProxy is displayed as running, while Content Filter is invalid

iOS

Yes, I sent an email to Apple Tech support as well as filed a bug report for this issue. Bug report number: FB17363627

I see now, thank you!