@userxwj5Ohv06w Have you tested the phone in Safe Mode to see if the light is seen there as well? https://www.samsung.com/us/support/answer/ANS00062983/
Been having this issue for months on Android 9. Samsung updated the UI over the summer, now when I gesture buttons selected I have a white light at the bottom of the screen. Family has six Galaxy 9/9+ so I thought that was on purpose to show you were to swipe.
Same problem. No I won't reset phone. It didn't fix the dozens of others in these threads. No I won't go into safe mode. Same reason. The light is do bright the phone is literally hot on the bottom. This is an obvious samsung flaw. They won't admit it. We all need to boycott samsung until they address their display issues.