Apple has released an article on it's support page on troubleshooting your AirPods Pro if they are giving crackling or static sounds. There has been a recent upsurge in complaint from owners that their AirPods Pro are not working well as expected when they first got them.
This week, Apple has released a couple of support articles that specifically mention troubleshooting steps to try, for users experiencing issues with Active Noise Cancellation or if they are hearing crackling/static noises.
Apple recently released new firmware for the AirPods Pro themselves, which will be automatically downloaded and installed when the AirPods are left connected to an Apple product for a little while.
For Active Noise Cancellation assistance, Apple again recommends updating your operating system to the latest version. Then, clean the mesh on the top of the AirPods Pro using a dry cotton swab. Apple says noise cancellation performance can be impacted if the mesh gets gummed up with earwax or other debris.
The cleaning steps should be useful if you have noticed a loss of bass response, or an increase in the amount of background noise (e.g. airplane sounds) that the Active Noise Cancellation setting fails to remove. If you clean the product and you still think you are experiencing worse than normal ANC, contact Apple Support.