Hi @Kate_93. That's very circular indeed. Try a Soft Reset to see if it disappears. This doesn't delete anything from your phone, it fixes any minor issues that may be occurring. To do this, hold the 'Power' button and the 'Volume' Down button, both together for ten seconds and your phone will restart. If it's still there after that, place your phone in Safe Mode which will disable third party apps and if your phone is fine during this, it indicates an app is causing it and we recommend deleting apps one by one until you find the culprit. Hold the Power button until Power Off is shown on the screen. Long press on this and it will change to Safe Mode, so tap on that and your phone will restart. To exit Safe Mode, restart your phone as normal.
Thank you for getting back to me, I tried the soft reset, the safe mode and then the full factory reset and it still appears, I guessing it's going to be a fault with the hardware of the phone. Really bizarre
In the developer settings make sure the "simulate display with cutout" option is set to default.
There are 6 display options, each blacking out different parts of the screen with exception of the default. I have no idea why this is a thing nor why mine got turned on, but after googling a bit I found that it was an easy fix.