Leaves are turning yellow from the bottom up and I...

For auto flowers you want to place your seed in the final pot size, they don't like transplants. From looking at your photos your temps / humidity seems fine as well as the light they seem to be building nodes at a healthy height and not bolting. Yellowing on the lower leaves would suggest that it is a mobile nutrient issue, if nutrients are your issue. Mobile nutrients are Nitrogen / Phosphorus / Potassium / Calcium and Magnesium The other types are Immobile nutrients which show on newer top growth leaves. Immobile nutrients are Manganese / Iron and Sulfur there are more these are just examples . From looking at the leaves it would suggest a very mild potassium or nitrogen deficiency but at this stage i wouldn't worry to much as its mild and you dont want to over feed them. Make sure you are not over watering or under watering as this can cause problems as well that look like other issues. Good luck and happy growing 😊