what is the lump on Kodiak

Noticed this yesterday afternoon. She's still eating, drinking and running around, but she's not been in the pond when they are out as much (but the pond is also gross, so not sure if it is linked).

It's soft. It may have moved down a little since yesterday, but I can't really tell for sure if it has or not.
I don't feel anything else anywhere else in her chest or belly.
A couple of somebodies have been laying off and on, but shorter days and they are molting, though I don't think she really has yet.

Weekend, so vets are closed and the vet we've used in the past for ducks... eh, not so useful, so probably wouldn't bring her there as we'd expect them to say, "Yep, it is a lump"

They get chicken layer, egg shells and peas (or other fruits/veggies, but recently just peas).