Canon 5D mark IV. Internal microphone problem?

grinbo

I'm New Here
Apr 26, 2019
21
2
Hello. Yesterday I went to a concert and did some video records. I've record sound on internal microphone. And everything was fine until one moment.At the half of one song sound went bad.
I've uploaded the part of the video here (bad sound from 23 second) : https://drive.google.com/open?id=1ji81z_jIMTGjJY_HMpvxpLn_barP0ohR
And I think the sound became worse than before, some kind of flat..
Camera settings is defaults.
Any ideas?