Hello Emilie,
AirPods are a great accessory, and ensuring that they're working as expected with your Mac, and being told you're sounding robotic. To clarify a bit further does this happen with all apps and functions? For example, if you have call forwarding set up on the Mac does it happen with traditional phone calls, FaceTime calls, or when using a conferencing app?
If you're unsure try recording a memo in the Voice Memos application, and playing the audio back to see if the issue continues. Also, make sure that the audio input is correct in System Preferences > Sound > Input. There is the possibility that the internal microphone of your Mac may be selected, and being used which may be causing this issue.
You can also find some great troubleshooting steps that may help with this issue in the following article.
If sound quality is reduced when using Bluetooth headphones with your Mac
Let us know the results, and we'll go from there.