While Apple’s redesigned keyboards in the new MacBook Pro models are made to be quieter, they also appear to be designed to prevent another problem. According to a document sent to Apple Authorized Service Providers and obtained by MacRumors, the new keys have a “membrane” underneath that helps “prevent debris” from getting into the butterfly mechanism.
“The keyboard has a membrane under the keycaps to prevent debris from entering the butterfly mechanism,” state the Canadian and European versions of the document. “The procedure for the space bar replacement has also changed from the previous model. Repair documentation and service videos will be available when keycap parts begin shipping.”
The US version of the document doesn’t mention the membrane specifically. However, it does link to another document entitled Butterfly Mechanism Keycap Replacement MacBook Pro (2018), which references the membrane under the keycaps as a method of stopping debris from entering the keyboard.