applied Romain's suggestions

<br><br>If you try installing a version of /e/OS based on a security patch that is older than the one on your device, you will brick your device.

Click on `Details` below for detailed information<br>

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<br><br>To check the security patch level on your phone with a locked bootloader, prior to installing /e/OS, open your phone `Settings` >> `About Phone` >> `Android Version` >> `Android Security Patch Level`.Then compare it against the level of the security patch on the /e/OS build as visible in the Downloads for the FP4 section below.

<br><br>Factors to consider to avoid triggering anti-rollback on FP4:

<br><br>The following values control whether anti-rollback features are triggered on FP4:

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<br> * Rollback protection errors trigger if you install an update whose version number is `LESS` than the rollback index's value stored on device.

<br> * The value of rollback index is `UPDATED` to match `ro.build.version.security_patch`'s value of the currently installed version, but only if the bootloader is `LOCKED`.

<br> * Rollback protection errors are `IGNORED` when the bootloader is `UNLOCKED`.

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Click the `Details` section to view some examples<br>

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Here are some examples to help you understand how anti-rollback features work:

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<strong>Example 1</strong>