गोविन्द भाष्य (श्रील बलदेव विद्याभूषण - अचिन्त्यभेदाभेद वेदान्त ब्रह्मसूत्र भाष्य सटीक)

The "avyakta" of this passage is not described as the object of knowledge. This
another reason for not interpreting this "avyakta" to be pradhāna.
Purport by Śrīla Baladeva Vidyābhūṣaṇa
Claiming that liberation is obtained by understanding the difference between
the the spiritual living entity, or soul and the modes of material nature, the
saṅkhya theorists affirm that one should know the real nature of pradhāna in order
to obtain certain powers. Because this passage from the Kaṭha Upaniṣad in no way
describes any of this, the word avyakta here cannot refer to the pradhāna of the
Saṅkhyites.
Sūtra 5
vadatīti cen na prājño hi prakaraṇāt
vadati-says; iti -thus; cet -if; na -no; prājño -the omniscient Paramātmā; hi -
indeed; prakaraṇāt-because of reference.
If someone says "This passage does describe pradhāna in this way" then I say
"No. That statement refers to the omniscient Personality of Godhead."
Purport by Śrīla Baladeva Vidyābhūṣaṇa
Someone may object: "Your contention that the word avyakta in this passage of
Kaṭha Upaniṣad cannot refer to pradhāna because the avyakta here is not described
as the object of knowledge has in no way been proved. Pradhāna is described in
this way in the very next verse (Kaṭha Upaniṣad 1.3.15):
aśabdam asparśam arūpam avyayaṁ
tathā-rasaṁ nityam agandhavac ca yat
anādy anantaṁ mahataḥ paraṁ dhruvaṁ
nicāyya taṁ mṛtyu-mukhāt pramucyate
"By meditating on the soundless, touchless, formless, unchanging, tasteless,
eternal, fragranceless, beginningless, endless, Supreme Great, one becomes free
from the mouth of death."