Downloading APKs from shady websites can inject malware, adware, or steal your Google credentials. Always use reputable repositories.
Usually because Google Play Services is outdated. Update Google Play Services from APKMirror first (version 22.x for Android 8.1). Google Play Store Android 8.1.0 Apk
These stores lack Google’s licensing checks, so paid apps you own may not install. Downloading APKs from shady websites can inject malware,