In this it is pointed out in this essay that the caste-oriented verses that deprecate the so-called lower castes and earmark inferior duties/menial work to them would not have been originals but latter-day interpolations for the simple reason that Krishna who propounded the Gita's philosophy himself was an Yadav, one among them.

To the uninitiated, Bhagvad-Gita was a discourse between Prince Arjuna and his charioteer Krishna, an avatar of Lord Vishnu, on the eve of the battle of Mahabharata, chronicled by Vyāsa through the medium of Sanjaya. In order to appreciate the Gita’s caste component, as opposed to its philosophical content, we must realize that whereas Arjuna was a Kshatriyā, perceived to be the second highest rung of the Hindu caste-ladder (below Brahmins but above Vaisyās), Krishna, Vyāsa as well as Sanjaya were Shudras, the supposedly low end of it

Given his belief in and concern for his caste purity, Arjuna could be expected to have voiced his fears to Krishna over the impending death of multitudes of his caste-men at the very outset in ch1 -
V 40. Die aged en masse dharma’s votaries / Won't that let go youth ours haywire?
V 41. Sex ratio adverse that war ensues / Turns women soft on caste barriers.
V42. Fallen women all go to hell / What is more their bastards rob / Posthumous rites of forebearers.
v43. Liaisons low of women wanton / Set our race on ruinous course.
However, Krishna being a Shudrā, would he have deprecated his own community in v32, ch9 in which it is stated that ‘women, Vaisyās and Shudrās could win the Lord’s favor through devotion’, sounding as if they are all in an inferior league. Doubtful, isn’t it?
Moreover, having earmarked the caste duty of Shudrās as menial work (v44 ch18), how come then Krishna would have assumed the role of a philosopher? Not only that, Vyāsa, the transmitter of the Gita to the world was a seer nonpareil credited with the compilation of the Vedas, which is no mean a task leave alone a menial work!
That brings into question the veracity as well as the credibility of v41 thru v46 of ch18 that describe the mundane duties of man on the basis of his caste (never mind Brahmin Dronācharya and his valorous son Ashwathāma were donning the role of Kshatriyās in the very battlefield at that time) besides the foundational caste-oriented v13ch4 in the Gita - chātur varnyam mayā srustam, the plain reading of which would have us believe that the Lord Himself created the four-caste system to suit the inclinations of a given soul towards certain earmarked calling of social and spiritual life in this world. And then, as a rider that is vague at the very best; Krishna supposedly said that though He is the author of it all, He should not be deemed as the doer.
In view of the above, it is absurd that Krishna in the Bhagvad-Gita would have formulated these caste biases and erected their functional barriers in ch18 through -
V47. It is better to do one’s own dharma, even though imperfectly, than to do another’s dharma, even though perfectly. By doing one’s innate duties, a person does not incur sin.
V48. One should not abandon duties born of one’s nature, even if one sees defects in them, O son of Kunti. Indeed, all endeavors are veiled by some evil, as fire is by smoke.
As detailed in my ‘Bhagvad-Gita: Treatise of Self-help’ sans 110 inane interpolations, the above and other deprecating verses were but mischievous insertions of the priestly class to subserve its mundane interests.
So, now it’s time for us all to follow Krishna’s advice to Arjuna in v63, ch18,
That thee heard of this wisdom/ For task on hand now apply mind.
--------------------------------------
Links to Bhagvad-Gita: Treatise of Self-help https://g.co/kgs/8f5awH