Diagnosis
This is almost certainly an audio sync or processing bug in the TV's firmware, especially common with Dolby Digital content from apps like Netflix or Disney+.
How to Fix It
Go to Settings > Sound > Advanced Settings. Change 'Digital Audio Out' from 'Auto' to 'PCM'. This forces the TV to decode all audio itself and send a simpler signal, which often stops the dropouts. Also, turn OFF 'Surround Sound' if it's on. If you're using the TV speakers, go to Settings > Sound and turn OFF 'AVL' (Automatic Volume Leveling).
If That Didn't Work
If you're using a soundbar or AV receiver via HDMI ARC, the handshake can cause drops. Try using an optical audio cable instead of HDMI ARC. If you must use ARC, go to the Inputs menu, find the HDMI ARC port (usually HDMI 3), and change its HDMI Format to 'Standard' instead of 'Enhanced' as a test.
Heads Up
The built-in Vidaa U smart system can get bogged down. A full 'Power Cycle' (Settings > Device Preferences > Power > Power Cycle) clears the cache and can help with audio/video glitches from the apps themselves. Do this every few months.