THIS IS NOT A BUG
I too do not have phone noise cancellation on my iPhone 13 Pro on iOS 15.
This is because the iPhone 13 series with the new smaller notch LACK THE MICROPHONE that is near the earspeaker/receiver. This missing microphone was used to measure sound close to the earpiece, such as your hand rubbing the side of the phone, wind noise
The old original notch found on iPhone 12 series, 11 series, XS/XR and X has this extra microphone built in the earpiece/receiver hidden under the earpiece speaker mesh.
If you have an iPhone 12/11/XS/XR/X and you look at the description for Phone Noise Cancellation under Accessibility and you will see it is only activated when you use the earpiece receiver, which means the proximity sensor activates the earpiece microphone, which also means Phone Noise Cancellation is disable when you are on speakerphone or using a Bluetooth headset.