Whats wrong with their beaks?

[Better with thyme]

Hi
I was given 4 runner ducklings. When they arrived this morning they had sores on their bills. The people who gave them to me said it was the "pigment " (im super new and can basically be told anything until I learn)
But it looks sore and open. Like a burn almost. I'm concerned about the other birds in my house too. They aren't in the same brooder but my house is tiny so they're across the room from each other.
3 out of the 4 have it but this one is the worst.

 

[Eggcessive]

Can you get a more clear picture in good light? @Miss Lydia and others know ducklings much better than I do. Perhaps they were being picked on or overcrowded at their previous home.

 

[Better with thyme]

Can you get a more clear picture in good light? @Miss Lydia and others know ducklings much better than I do. Perhaps they were being picked on or overcrowded at their previous home.

Sorry. There's a ton. The 2 seem to have it the worst. There's a yellow guy with just a touch but he wont stay still. I'll keep trying. The little black guy wasn't eating so i gave him a dropper of electrolytes and he's perked up a bit.

 

[Better with thyme]

I was able to get a few clearer ones. And the yellow guy.
Sorry if thats too many. I'm hoping it isn't something contagious and I can help them.
I also hope it isn't common or I've lost my faith in people.
The guy who gave them to me is from a sanctuary and gave them to me as a kindness after a horrible loss I had yesterday. He said it looked like their colouring but as a newbie it took me all of 30 seconds to see it was problematic.

This may have been a short lived failed dream if the tiny amount of time I've had turns into nothing but heartbreak.