Logitech Unveils MX Master 4 Special Developer Edition | TechPowerUp
https://www.techpowerup.com/354198/logitech-unveils-mx-master-4-special-developer-edition

"... Logitech has also added a few Easter eggs, 0xFF + 1 referencing World Programmers' Day, 09.17 for the Linux Kernel release date, and !04.01 for World Backup Day. ..."