Yellow flower

This is exactly how cannabis seedlings grow and is not a problem. The reason for the pale colour in the new leaves is due to the chlorophyll still forming in those areas. It is not a nutrition issue and your plant does not need fertilizing at this early stage, as there is nothing to "fix".

That's totally normal, no need to worry. All new growth come out light green. Best of luck

And btw, since it's an auto and VERY young, start it out with 1/4 strength nutes... increase that to 1/2 strength next week if it tolerates the nutes this week ... and then full strength the week after adding in bloom nutes week 3-4... Once it goes into flower, it won't need as much nitrogen so you can lax off the grow nutes and pump up the bloom nutes.

Imho nothing to worry about.

If you'd link questions to a diary, we'd have a better chance of helping out as it would give us far more information! On balance, though, your plant is hungry and needs some grow nutes with a good NPK ratio...