Alarm keeps muting itself for no apparent reason

Hello, several times a day I find the volume slider on my alarm has gone right down to zero, when I never choose this option myself. I use my phone as an alarm clock but am really struggling to trust it as its such a reoccuring thing and I can't think of the reason causing it. I've looked around in settings but couldn't see an obvious fix.

Does anyone else have this issue and perhaps knows a fix?

Thanks