We are aware that 450X has a deliberate error with it’s speedo. It shows 90kmph in the dash while a VBOX will record only 80kmph. This could be due to the same reason. Again looks like display is lagging which is common with Ather too. A restart might help to bring that up to speed.
Refer this - What's Your Top Speed on Ather? 🤔 - #21 by raghav.srinivasan