Q.tomato seedlings
Planted some heirloom tomato seeds. When they came up, some were white leaves and some green in the same container. What’s up with that?

The white or lightening of the seedling leaves could be due to cool temperatures or too bright of sunlight.
Here are some articles with more information.
https://www.gardeningknowhow.com/edible/vegetables/tomato/tomato-leaves-turn-white.htm
https://www.gardeningknowhow.com/edible/vegetables/tomato/growing-tomatoes-from-seed.htm