Apple has been slowly tightening the screws on app notarization (code signing) requirements for running apps on macOS. To do it properly you need to be a registered developer ($100/year), and they're certainly not making it easy if you don't have access to a Mac.

https://support.apple.com/guide/security/app-code-signing-pr...

> On devices with macOS 10.15, all apps distributed outside the App Store must be signed by the developer using an Apple-issued Developer ID certificate (combined with a private key) and notarized by Apple to run under the default Gatekeeper settings.

Re: Developer ID Certificates: https://developer.apple.com/help/account/certificates/create...

I suspect the friction that users are facing are due to dodging the above requirements.