@Jainesh_Softvan
Okay...I got a chance to look at your scenario. It seems the items in the Gallery in the component are an issue in a form! This does not surprise me as Galleries in forms have a long known bug on them, so a component with a Gallery causing massive issues is not a surprise.
I was able to duplicate your problem when I used the component you had. I was able to reduplicate it when I started from scratch and basically built the same thing.
Now - I initially answered you that it works fine. The reason I did is because the component I had checked had a Rating control in it - NOT a gallery. That worked perfectly fine!
I even reproduced that it was fine by removing the Gallery and putting a Rating control in. I changed the RatingItems property on your component to be a numeric input property. The Rating Control in the component Max property was set to Parent.RatingItems and I set the RatingItems property to a default of 5.
I changed the Output property to RatingControl.Value
I also added another number property called Default and set the Default property of the RatingControl to Parent.Default. I set the Default default value to 2.
Now, back to the Form - I added the component to each datacard. I also added a label in the datacard to reflect the SelectedRating value of the component...and all worked perfectly!

So...this is seeming to be the curse of the Gallery in a Form that is the issue. I would submit it as a support request. The response will most likely be the warning not to use Galleries in a Form, but, in my opinion - it's still a bug that should work!