Iphone 8 colour fades

My iphone 8 colour faded from all four side front facing. I just noticed it today.

I recently started using a new adapter which was replaced under warranty. Not sure if it is related to this.

for the first 2 days I noticed adapter was heated up but later it was working as smooth. Not sure if this issue due to adapter.

also this device is under warranty period can it be replaced??