@M guy: If you have recently installed any files or apps from an unauthorised third party source, then please try uninstalling them to see if you notice an improvement. If the problem persists, then I recommend backing up your Galaxy A21s and performing a factory data reset. This will restore the phone to it's default settings, and should resolve any existing performance issues that you're having. For a guide on how to back up your phone and restore it to its factory settings, please click on the link below.
