Google doesn't like Apps like AppCloner, Lucky Patcher, APK Editor. And since Play Protect is from Google, well they block it. So just ignore it and install anyways.
You getting a virus warning about a mod? In most cases, that's a false positive. The most reason is some modders protect their mods to prevent someone leeching their code, but protection caused anti-virus to be confused and flagged the mod APK as a virus There are modding websites that...