Audio works on some platforms but fails on others. What can it be?

Hi! I'm new on fcp.co. I have a MacBook air (M2 2022- Monterey) and I edit in Final Cut (10.6.5). When I import mov files from my Canon 6d, the audio works fine on this computer. I upload the videos to YouTube and it works fine too.

However, some people are complaining in the comments about the inaudible audio with huge hiss when streaming my files on lives and on the links that I posted on YouTube.

I tested my YouTube links on my Mac Mini (2018 -Mojave) and it didn't work either. On iPhone 6s (14.4.2) it didn't work too.After that I tried to open the original Canon 6d movs files on my Mac mini on Quick Time and to my surprise the audio was very hissy (?!!) .

I tried to invert the audio phases, converting the mov files from camera to mp4, but it still didn't work in others platforms. What else can I do? 

Please, help me. Thanks!

Here is the video where I played the same Youtube link on two devices. On Macbook (M2 2022- Monterey) everything works, On Mac Mini (2018 -Mojave), Canon 6d audio files doesn't work, but the audio files that were recorded in the studio with other camera worked perfectly.