Apple surprisingly updated its MacBook Pro lineup a few days ago, offering new 13- and 15-inch models that came with a "quieter" keyboard - although further testing indicated that it does not sound much different from the old one. A couple of days later, private company iFixit discovered that a thin silicone membrane covers the problematic butterfly mechanism under the keyboard, presumably to protect it against dust. This claim was backed up by an Apple patent that describes a similar sort of protection mechanism.
Now, MacRumors has obtained an internal document in which Apple has confirmed that the third-generation keyboard in 2018 MacBook Pro models is indeed equipped with a membrane to "prevent debris from entering the butterfly mechanism".
The document is noted to be the Service Readiness Guide for the latest MacBook Pros, distributed to Apple Authorized Service Providers. An excerpt from the Canadian and European versions of this document reads as follows:
"The keyboard has a membrane under the keycaps to prevent debris from entering the butterfly mechanism. 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."
Although he U.S. version of this guide does not explicitly refer to the membrane, it does contain a link to a separate internal document that cautions against tearing of this membrane, as that would require "a top case replacement".
Even before the release of this document, it had been highly speculated that the membrane is in place in order to fix the "sticky key" issue being faced with previous keyboards. Incidentally, Apple recently stated that the third-generation keyboard is exclusive to the new line of MacBook Pros, and therefore, defective keyboards can't be swapped with the latest one.
The tech giant has not yet publicly confirmed that protection from debris is the actual purpose of the new design. Of course, it was quite unlikely that the company would have done so before, considering there are currently several lawsuits against it with regards to the defective keyboards. Now, however, the possible ramifications of this leaked document can turn out to be quite interesting.