Is your loudspeakers through a soundbar, Bluetooth attached speakers, receiver, just TV speakers? I’d make sure all devices are using the latest software, from the AppleTV to the TV to the soundbar - any device between the AppleTV and actual speakers update.
Did the issue crop up around a specific time of the AppleTV update or update on the TV? I’ve seen “Auto” negotiate a standard have issues on a number of devices over the years.
From an A/V troubleshooting aspect, there’s usually multiple devices in the A/V chain. I try to identify what specific device may be causing the issue to focus my attention on the right one (It may or may not be the AppleTV). While unlikely, do try a different HDMI cable. Next, eliminate the soundbar or audio receiver or Bluetooth speakers -> test using just the TV speakers (if possible). If any test scenarios eliminates the issue, request assistance from that device maker too.