Nah they'll be right. No point chasing minor deficiency. They are moving better then most here at three weeks so I don't see the point in messing with em tbh. They'll pick up
I get this same mg like issue every time I start in thrice recycled medium. They snap out if it once they get their legs around week 3-4.
Guys leave it as it is.
We discussed about his plants on his thread. @Vick_Vinegar was not the best idea to post those pics here, better leave it on yours and discuss there, now y overtake @Jakee123 thread, focus on him please.