Why exactly is a specific app marked malware?

Hi all, I have a specific app, and only one, that I have had installed for many years and have used successfully that recently started popping as a possibly malicious software. Why would a specific app pop, and how do I know if it is a false positive? The app in question is called " decked builder " . It is an app for organizing Magic the Gathering cards. TYIA.

What device and OS version are you using?

Did that app recently get updated?

You can use this Norton Support article to find how to report false positive detections. Submit a file or URL to Norton