Black screen mirroring since update ?

Salutations Vizcaya1, 

For issues when running beta software you can provide feedback about using Feedback Assistant. Apple Beta Software Program

How do I provide my feedback to Apple?

The iOS, iPadOS and macOS public betas come with the built-in Feedback Assistant app, which can be opened from the Home screen on your iPhone or iPad or from the Dock on your Mac. The Feedback Assistant app is also available from the help menu of any app by selecting Send Feedback. If you’re running the tvOS, HomePod software or watchOS public beta, you can submit feedback through the Feedback Assistant app on an enrolled iPhone, iPad or Mac. When you experience an issue or something does not work as expected, send your feedback directly to Apple with Feedback Assistant.

You can also remove the beta software and install the latest public release of iOS. The following article goes over removing the profile, then restoring your iPhone to remove the software itself - How to uninstall iOS or iPadOS beta software

Thanks. 

Greetings Vizcaya1, 

We’d like to recommend a bit of basic troubleshooting to get started with. 

1. Make sure your iPhone and your AirPlay-compatible device are both up to date. Update your iPhone or iPad

2. Restart all devices that are involved. Restart your iPhone

Then if the issue is persisting, let us know if what you’re encountering is happening in a specific app or with all apps, both Apple-developed and third-party. 

Thanks.