https://phys.org/news/2018-05-apple-class-action-lawsuit-defective-macbook.html

It was brought by plaintiffs Zixuan Rao and Kyle Barbaro, each an owner of a MacBook Pro. The suit charges that complaints of keyboard failures began to occur soon after the 2015 MacBook was launched and that despite being aware of the keyboard defect, Apple equipped future- model MacBook and MacBook Pro laptops with the butterfly keyboard and continued selling these machines to consumers at premium prices.

The keys on these butterfly mechanism models, which felt flatter than other models when introduced on the 2015 MacBook, allowed for a keyboard that was 40% thinner than one using the "scissor" type mechanism that was the design norm.