Hi
@HelsAre you able to perform other actions when the notification bar stops swiping downwards? e.g. is the phone freezing or is it just the notification bar that stops working as expected? I'd recommend performing a Soft Reset if you experience this issue again to address any temporary software problems (press the Volume Down and Power buttons for around 10 seconds until the phone restarts). If the problem persists then restart the phone in Safe Mode via the following steps and monitor the phone's performance for a few hours. This will temporarily disable any third party apps therefore if you notice an improvement then I'd recommend deleting any recently installed third party apps to remove any potential compatibility issues.
SAFE MODE: Turn the device off > Press and hold the Power key > Release the Power key when theJ5 logo appears > Press and hold the Volume Down key immediately after releasing the Power key > Continue to hold the Volume Down button until the device finishes booting.