Input label persistently showing on TV after TvOS 15.4.1 update

Hi

I have an Apple TV 4K (newest one). It's just updated to TvOS 15.4.1. Since then, the input label for the HDMI port that the Apple TV is connected to persistently shows up in the corner of the TV screen, it doesn't fade out as it does normally.

In my case, the text 'AMP' shows up in the top left corner of my Panasonic TV and doesn't disappear whenever I use the Apple TV or any of its apps (the Apple TV is connected to my sound bar amp, and the amp connects to the TV's ARC HDMI port, I've labelled the input 'AMP').

Other HDMI inputs are fine. ie, they show up for a few seconds then fade out. Does anyone else have this problem?