Unfortunately this is normal with OLED displays when the background is completely dark.
As the pixels of the background are switched off they take some time to power up again, this is then visible as the smearing you see.
Yep, long been an OLED issue. I remember going back to 2010 with my Nokia N8-00 Symbian smartphone this was an issue, it became more prominent with the Galaxy S4 if my memory serves me correctly, as we got higher resolutions OLEDs.
I think it’s actually become better in more recent displays in the last 2 years or so, it was really bad on the GS4.