What is going on here?

[Logar]

One of my 3 week old chicks is having mustard yellow poops. I don’t know what is happening. I am really worried that it could be a liver issue or something.

 

[Logar]

I should mention that if it wasn’t for the poop you wouldn’t even know that there could be something wrong. She runs and jumps around, “flies” aka runs around flapping her wings with everyone else, eats, drinks, etc.

 

[Eggcessive]

I think that it is just a cecal poop. Those come from the 2 ceca between the small and large intestines, where the food is fermented during digestion. They can come in all colors, are very stinky and sticky. In this article you can see the ceca in the pictures:
https://www.backyardchickens.com/threads/versions-of-chick-chairs-please.1166308/

https://www.backyardchickens.com/articles/cecal-vs-regular-poop.75555/