Hi Marc_O_Polo,
For help with Continuity Camera and third-party apps, you may need to reach out to the app developer directly to report the issue. Before you do, test the wireless connectivity with a built-in app, and view helpful information below also found in the article here: Continuity Camera: Use iPhone as a webcam for Mac - Apple Support
"If Continuity Camera isn't working as expected
- Make sure that your iPhone and Mac meet the system requirements.
- Make sure that your iPhone is properly mounted.
- Install the latest macOS updates, iOS updates, and updates for your video app.
- If you haven't unlocked your iPhone since it last restarted, unlock it, then lock it again.
- Plug your iPhone into your Mac.
- Restart your iPhone or Mac.
If you get a notification that iPhone Wi-Fi disconnected
While using Continuity Camera wirelessly, you might be notified that your iPhone has disconnected from Wi-Fi to optimize Continuity Camera. Your iPhone then uses its cellular data connection for background networking tasks like email and messages. To stop or prevent this rare occurrence while using Continuity Camera, plug your iPhone into your Mac or turn off cellular data on your iPhone."
You can also check your Handoff settings with this article: Use Handoff to continue tasks on your other devices
If needed, the steps here will help you reach out to the app developer: How to contact an app developer - Apple Support
You can also view their support website here: Zoom Support
Cheers.