Significance of Mutable
In Vedanta, the term mutable denotes the quality of being changeable. This concept applies specifically to the subtle and gross bodies, which are subject to transformation and evolution. In contrast, the immutable Self remains constant and unchanging. Thus, the distinction between the mutable aspects of existence and the unalterable nature of the Self is a key component of Vedantic philosophy.
The below excerpts are indicatory and do represent direct quotations or translations. It is your responsibility to fact check each reference.
Hindu concept of 'Mutable'
Mutable in Hinduism indicates the quality of changeability, applicable to the subtle and gross bodies, while contrasting with the immutable nature of the Self, which remains constant amidst transformations.
From: Taittiriya Upanishad Bhashya Vartika
(1) Mutable describes the quality of being changeable, which applies to the subtle and gross bodies but not to the immutable Self.[1]