Yellow marks??

There are many things that can cause this at such a young age. especially If any one of the basics needed for proper growing are not attended to. Their twisting, cupping, turning yellow. She's under a lot of stress.

begining of Ca excess and K,Mg lockout my opinion is to stop using calmag at least for a week - 1.5 and then cut its ppm in half

Maybe a bit low on K? would want to see it progress more to be more confident. if it is more interveinal chlorosis with less damage around serated tips of leaves, i'd look in another direction. Leaf symptoms are not discrete. You need more information than that to be confident about a diagnosis. Drying pattern indicates poor watering habits too, which could be a contributing factor. Always fully saturate. Never partially water. Wait for top layer of coco medium to start to change color and repeat -- never allow wilt.. if it wilts you water sooner, obviously. Not doing so trains superficial roots and elevates risks of rootzone problems. If this is a soilless grow, you need to also have 10% runoff each time and always fertigate with complete diet. Watering should be the simplest thing you do. if you are whimsically choosing to give it X Liters per day or similar, that is the wrong way to do it. You give what is required to accomplish the task and the time between irrigations should be something you observe like dryness of top or some minimum weight loss.

Wird wahrscheinlich ein Mangel sein nur die Ursache wäre jetzt die Frage😅 Teste mal den PH Wert deines Gießwassers und eventuell drainwasser also das was unten aus dem Topf kommt und schau ob das passt 6.2-6.5 wäre anzustreben! Falls was damit nicht stimmt, solltest du korrigieren und das Wasser anpassen und gegebenenfalls das Medium einmal "auswaschen“ Wenn es kein PH Problem ist, wird es ein Mangel sein! Ich wünsch dir viel Glück beim Grow ✅