The security threat is related to the debug signing key. Switching to a private sign key will solve it.
The "old app" warning is related to low value of targetSdkVersion in the manifest editor.
Thank you.
1- I uninstalled b4a bridge from my mobile
2- I changed the target sdk in manifest to 28
3- I created an new key in private sign key tool
4- Then i recompiled and moved latest api file.
It installed but not worked correctly yet.
Then, when i run the app it showed a message "waiting for IDE debugger to connect..." And then it showed a black screen
After all I changed the debug mode to release mode
) and pressed F5 and it worked.
Thank you for your help and for solving my elementary problem.