Picture and sound asynchronous after import?

I'm trying to import videos from my iphone to my laptop.
So far everything has worked out well, the videos are shown to me etc.

Only with a single video does the sound not match the video material. The video does not start directly either, but is fixed for approx. 1 second in the initial picture and then begins only while the sound has been playing for a long time. What can that be and what can I do about it?

Probably a mistake in the video recording… Maybe you can fix that with a new conversion, z. B. With Avidemux, the asynchrony can also be remedied there.