Growing 2 plants, 3rd week in to the grow. one lo...

Yup i think indeed overwatering or the pot hasnt got any holes and cant drain any excess moisture.

Must be a pH thing... Normally that coloring is sulphur deficiency which is rare. Try correcting Ph to 6.2 if it's soil and feed it 1/3 minimum amounts of base nutes.

I can't tell, from your diary, whether this is an autoflower or a photoperiod... but it looks to me like you've got some deficiency of a micronutrient (it really doesn't matter which one, tbh) in the plant that is yellowing (the other looks fabulous)... and THAT is indicative of a PH that is not in a good range (6.0-6.5). Make sure anything you give them (water/nutes) is ph'd to within that range and you should see some improvement. If these are autoflowers, be cautious when you start to give them nutes - they don't like very much so always start off with about 1/4 the dose recommended and increase slowly. And since you're wondering why there's a difference between the two, I think it just falls to genetics, especially if you've done everything the same. I have one grow (Lemon) with 3 plants and one of them was and remained stubbornly lime green for it's entire life.... nothing I did resolved the color issue but there was no other problem with the plant and it, actually, gave me my best harvest... strange to say the least! Treat each plant as a separate grow... give each plant what IT is telling you it needs/wants/demands... they may not need water at the same time, they may need different levels of nutes... just pay attention to each of them individually.... and good luck!

Die kleine hat wohl nasse Füße 😅 So kleine Ladys reagieren sehr empfindlich auf zuviel Wasser. Meist brauchen sie nur 1 mal die Woche wirklich gegossen zu werden.

Looks like overwatering. Give them 5 days without water, so small plants need water about one time in 4-7 days. Also check your pot for holes on bottom, its necessary for plant to breath.

Could be from Over watering