The microphone is used to record videos with sound and upload them through attachment fields.
The microphone feature is already enabled for Android & iOS. You can't disable it since it's a website, and you need it by default. Sometimes Apple may reject you and require a more detailed explanation on how to use it.
  • Permission description - The permission description text should explain to the user why your app needs that permission. Refer to Apple's guidelines to avoid potential rejection.

Rejection example: