If you are running macOS Monterey, you now have the ability to AirPlay your presentation directly to your Mac screen (https://www.litsoftware.com/blog/2021/11/3/present-trialpad-to-your-mac-laptop-screen-with-ipados-151-and-macos-monterey). While this can be a benefit in some settings, it can prevent you from sharing your iPad presentation using Zoom's built in AirPlay.
If you want to present to Zoom you will need to turn off the ability to have your Mac act as an AirPlay Receiver. You can do this by going to System Preferences > Sharing and UNCHECK the box next to AirPlay Receiver.
If you later want to present to your Mac again, just go back into System Preferences > Sharing and CHECK the box next to AirPlay Receiver.
Here is a short video tutorial about using TrialPad to present evidence over Zoom: https://support.litsoftware.com/hc/en-us/articles/360060681373-VIDEO-TrialPad-Presenting-Evidence-Over-Zoom