Sorry to hear that. It likely has to do with Mac's security settings (Gatekeeper) not trusting an unsigned application, which is more common for recent macOS versions. It happens to a lot small indie devs that aren't part of the Apple Developer Program.
Here's a guide that might be able to help: https://osxdaily.com/2019/02/13/fix-app-damaged-cant-be-opened-trash-error-mac/