USB connection of LG 5K is lost

I use a MacBook Pro (16-inch, 2019) (Catalina 10.15.7) together with an external LG UltraFine Display 5K (latest firmware).

When I use the LG builtin camera for a while (30 min to several hours) in Zoom.app or Photo Booth.app, the connection to the USB hub in the display is suddenly lost. Once it happens, all the LG USB devices, namely, the builtin camera, microphone, and speaker, are disconnected but the USB power delivery to the MBP and video connection (Thunderbolt 3) keeps working.

Indeed, executing the command "system_profiler SPUSBDataType" from Terminal.app cannot find any LG USB devices after this issue happens. But disconnecting and reconnecting the Thunderbolt 3 cable immediately makes the Mac recognize the USB connection, and I can use them in my Zoom meeting again.

I asked the LG support but they could not reproduce the problem in their lab. They replaced the main board just in case, but the problem still exists in my environment.

I can reproduce the issue with my two MBPs. The other one is MacBook Pro (15-inch, 2017) (Mojave 10.14.6), which has a similar configuration with the Catalina MBP as it was my previous main machine.

If LG is really unable to reproduce the issue, the root cause may exist in my side. But the issue can be reproduced by my two Macs, and I do not have a clean environment at the moment.

I would like to know if anyone has the same issue or any suggestion. I tried SMC and NVRAM reset.