One of the GoPro Hero 7 added features is called Hypersmooth (https://gopro.com/help/articles/block/what-is-hypersmooth) which is their method of audio/video stabilization. However with this feature enabled, we have seen audio precede video on the HDMI output of the camera as this feature requires more CPU usage from the camera, and this feature may be best suited for direct recording to the SD card.
To enable or disable this feature, tap on the touch screen to show current settings, select the the bottom bar that shows resolution and framerate (typically something like 1080|60|L), and tap the Stabilization button. This will toggle the feature off and on. If the feature is on, it will show a small square with an accent on each corner under the resolution and framerate bar. The other two icons that can appear here are the low-light management (small half-sun) and Pro Tune activation (will show PT icon).
Please note this article is based on GoPro firmware version 1.61, and it's possible more recent iterations of the firmware may fix this limitation.