In UE5.3 and later, afterimages may appear incorrectly scaled when the screen resolution is not 16:9.
This issue occurs because the default Field of View (FOV) axis setting was changed starting with UE5.3.
As a workaround for now, you can use the previous FOV setting by adding the following lines to your DefaultEngine.ini.
[/Script/Engine.LocalPlayer]
AspectRatioAxisConstraint = AspectRatio_MaintainXFOV
The source information is here.