How to fix 'Blocked by Play Protect / This app may be harmful'

I've released an app on Play-store and another market but in 2 recent releases just users of that market have faced to this Warning: "Blocked by play protect / This app may be harmful / Install anyway" How can I get rid of this? I've even set V1 and v2 Checkboxes during making the release and I'm doing exactly what I've done for previous versions.(Same Key store, Alias and Password) Is there any relationship between this problem and accessing to keyStore info by third-party? If yes, How?
If no, what is the solution other than submitting "Play Protect Appeal Form" every time after each update and missing a large number of users and customers?! Thanks in advance.

First you need to understand how play protect works in google play.

Refer this site for more information https://www.google.com/about/unwanted-software-policy.html

• Remove all unnecessary external library before building release application.
• Check for any third party URL you are trying to invoke in application.
• Remove unnecessary permission.
• Use same keys you used for previous version.
• Your application should have proper security guideline setup like tokens.
• You should remove any code that block hardware
• You should not interact with system using shell commands.

In the end just https://support.google.com/googleplay/android-developer/answer/2992033