I am a three letters word (small riddle)

Question

I am a three letters word,
why you can't digest me?

I am a concept of, and palindrome,
exists in a state of incomplete transformation.

you find me, with a little change, in your mother,
change a letter to become, a star, popular.

I am uncooked in the ancient speaking,
you can find me with a little digging.

What I am?

Hint#1:

You can find me in one of the Vedas

Answer 1

I think this the word is

ama

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

Answer 2

It is

YAM

I am a three letters word,

YAM has 3 letters

why you can't digest me?

YAM (raw ones) is difficult to digest

I am a concept of, and palindrome, exists in a state of incomplete transformation.

Reverse Y A M to get MAY, which in an incomplete form of 'MAYA'

you find me, with a little change, in your mother,

Mother is MAM and with one letter change it becomes YAM.

change a letter to become, a star, popular.

To be explored ...

I am uncooked in the ancient speaking,

To be explored ..

you can find me with a little digging.

Yam can be found with little digging (underground).