This is the 60% layout used by u/merlin36, host of the MechMerlin YouTube channel.
It has 5 layers, base QWERTY, base HHKB, FN 1, FN 2(HHKB), and an arrows only layer.
Merlin's KC60 was acquired from Massdrop: https://www.massdrop.com/buy/kc60-mechanical-keyboard and is the Co-Star stabilizer version
If you would like to program your KC60 using the manufacturer recommended approach, please follow the guide on keychatter: https://www.keychatter.com/2015/07/05/programming-the-kc60/.