Shotcut exports as music file at 100% quality but at 99% its an mp4 file

can you please help me?

I would like to help but I do not understand the question well.
For more effective help, more information would be advisable.
Some screenshot would also make things easier.
A greeting.

It is a video file at 100%, but it using a mode of the video codec (lossless) that most media players do not support. If you need 100% (lossless), then it will work as-is as long as whatever you are doing with it is compatible. Otherwise, you need to use <100%. IT IS WHAT IT IS.

Duplicate of