Huawei
Allow App Installs From External Sources auf Huawei
EMUI treats every app that can request installs, such as a browser or file manager, as its own source. Each source needs a separate permission before it can trigger an installation. This is why the warning appears even when you already trust the app or file you downloaded.
To change this, open Open the settings ➔ Tap on Security ➔ Tap on More settings ➔ Tap on Install apps from external sources. You will see a list of apps that are allowed to request installations, such as your browser or file manager.
Tap Choose an App, select the app you used to download the APK, then use the switch to Activate or deactivate the Allow app installs permission for that app only.
This setting only affects the app you selected. Other apps stay blocked from installing files until you repeat the same steps for them.
Leave the permission off for apps you rarely use to sideload files. Turning it on permanently for a browser or messaging app increases the risk of installing unwanted software from unverified links.