I think this the word is
I am a three letters word,
Yes, and straightaway hidden in clear sight : I am a
why you can't digest me?
In ayurveda it may be a toxic byproduct generated due to improper or incomplete digestion
I am a concept of, and palindrome, exists in a state of incomplete transformation.
Yes a pal., and in ayurveda, is the concept of something in a state of incomplete transformation.
you find me, with a little change, in your mother, change a letter to become, a star, popular.
A short word for a mother is a ma. Not sure about the second part.
I am uncooked in the ancient speaking, you can find me with a little digging.
"Ama" is a Sanskrit word literally meaning "uncooked" or "undigested".
Maybe find with a little digging is because ama is hidden in this puzzle in the title and lines 1&3
Hint #1: You can find me in one of the Vedas
There are four Vedas: the Rigveda, the Yajurveda, the Samaveda and the Atharvaveda