Phosphorus def in veg?

Hey So I would definitely lean towards a phosphorus deficiency....but it can sometimes be connected with calcium too. Personally when i started regularly using a calmag supplement my plants were much happier. Your plants don't use much phosphorus in this early stage and if you're giving a regular regimen of the flora this shouldn't be happening. Double check the outgoing runoff ph and if its coming out in the right range then I would highly suggest recalibration of your ph pen. They usually need it done every so often depending on how often its used. I usually recalibrate at least once a month because i had a ph pen go off and it caused total havoc on all my leaves. Happy growing.✌️