Purple Leaves - Is this Normal? Or Maybe Desirable?

Day 35 of Flower
Strain: Dog Kush
Lights: LED COB 3590 - 600 Watts
Distance to light - 2 Feet
Soil: Fox Farms - 5 gallon pots
Nutrients: Fox Farm, Big Bloom, Tiger Bloom, CalMag (500PPM)

I have never seen leaves this purple. This is the 1st time running this strain and 2 other plants (different Strain) in the same SCROG are not showing the color change. Is this a deficiency? Or is it a normal or even desirable trait?

The plant seems to be very healthy and doing great.

Any input to help solve would be greatly appreciated.

I Like Purple doesn't look bad to me.

give them some phosphorus, their eating themselves

Either PH is off or you're underfeeding them. Next time mix in some dolomite lime with your soil, 2 Tbl per gallon of FFOF.