Again a small but noticable problem. Listen to the video I provided with full volume and you should be able to hear for the first 3 seconds a weird higher pitched noise. Then suddenly it just dissapears. Along with this I noticed microphone volume in Snapchat seems to have been lowered significantly.
I was unable to recreate this on my test unit. I tried 4K and 1920 x 1080. What settings are you using? If you take multiple videos back to back, do you hear that noise in the first three seconds of each one?
The first video was shot in 1080p but it's the same in 4k. It happens every time but only in the stock camera app. When recording with Snapchat or the messenger camera it doesn't make the sound. However as noted before the volume is really low now for some reason.
Here's another 1080p video with the same 3 second sound. I can confirm its the same on 4k. 60 FPS and 30 fps makes no difference as well. V_20191112_011323_ES0.mp4