Are you saying that the sending device is an XIAO not connected to a PC and the receiving device is a PC?
If so, what application are you using to receive on the PC?
@msfujino
I think the shortest way to solve your problem is to first complete a sketch that can be reliably connected, without the microphone.
In your previous post you used bluefruit.h, but in your upcoming post you use ArduinoBLE.h?
There is no consistency and I have no idea what on earth you are trying to do.
What do you think about this?