If you can't stand iOS 12.5.2's performance on your iPhone 6 or iPhone 6 Plus you no longer have the ability to downgrade your phone's software.
Apple has stopped signing on iOS 12.5.1 which means you can't drop your device back to the previous version of iOS 12 in an effort to improve its performance.
Unfortunately, the company's also stopped signing on iOS 12.5 and older versions of iOS which means there's no way to drop your device back down to those versions.
iOS 12.5.2 might be the final software update for the iPhone 6 and iPhone 6 Plus so if you're running an older version of iOS 12 and you're having a good experience, proceed to the new firmware at your own risk.
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