Plant problem HELP

[Cypher17]

Okay I just got done transplanting it but before I did this is what it look like I’m doing 18/6 light schedule haven’t fed yet I’m on day 21 right now this is how they look what is that

 

[Capn-Crunch]

You have a slight Mg deficiency

 

[Cypher17]

You have a slight Mg deficiency

I’m getting different answer one said potassium

 

[Cypher17]

You have a slight Mg deficiency

could it be this look like nutrient burn or sum plant look kinda like this running along the edges of my leaf