I dont raise ducks, only chickens. But i think it would depend on the cause of the limp. If its wild, it could likely be an injury from a predator attack, but its also possible it was born that way. I dont know of anything you could do to help it. If there's obvious signs of injury, you could try to clean the wound, but i dont think there's much you can do.
Discussion
I guess it was an attack or accident or some sort, she is not born like this. Today is the first time I see her not using one leg. I didn't see a wound, she is more wary than usual and doesn't let me come close. I don't pursuit her to not stress her any further.
Tried to give some food and water
IMHO, if it can still fly, it'll be ok against attacks.
Would not recommend intervention.
If you cannot see swelling, bleeding or any apparent injury, maybe you could watch the situation for a couple of days, while continuing providing food, and see how it evolves. If it worsens, then contact the rehab center. Probably it is a minor injury and will heal on its own.
In any case, the duck is lucky to have you around.
Yes it still can fly - I wasn't sure before but she lifted off after resting in my garden. Thanks for the comment, I will try to check on her the next days if I see her 😊
And many thanks for the kind words, I was worried all day lol, this made me feel better
Forgot to say: thanks for the reply 😅