What is this? Clones in a ez cloner (white like crust)

[BluePowerRanger]

It’s like a white crust I can rub it off and it just crumbles at my finger tips. It’s in a few new growth tips which also crumbles away..

Temp in room 65 ish
Humidity 50%
Passive lighting from a hlg 65

that’s over 2 foot away vertically and 18 inches or so horizontally