As I discuss in this answer, one of the early movements that was important to the development of Vaishnavism was the ancient Pancharatra movement, whose sacred texts consisted of detailed procedures to worship the sage Narayana, an ancient incarnation of Vishnu. Since the Pancharatra texts originated from Narayana himself, they are followed by pretty much all mainstream Vaishnava Sampradayas, whether Sri Vaishnavas, Madhvas, Gaudiya Vaishnavas, etc. But as I discuss in this question, there's another group of Vishnu-worshippers who worship Vishnu according to an entirely different set of texts, the Vaikhanasas. The Vaikhanasas form a tiny minority, but they run a lot of famous Vishnu temples including the world-renowned Tirumala Venkateshwara temple.
Now as I discuss in this question, the Vaikhanasas trace their origins to the now-lost Vaikhanasa Shakha of the Krishna Yajur Veda. But the Sutra texts of the Shakha still survive; you can read them here. In any case, in this excerpt from the Vaikhanasa Dharma Sutras, Yogis are classified into three categories: Saranga Yogis, Ekarshya Yogis, and Visaraga Yogis. Visaraga Yogis are described in very harsh terms:
The Visaraga-ascetics (are called thus) because of their manifold proceeding, their manifold teaching, their going on wrong paths. In former times Prajāpati, in order to conceal his instruction, created the doctrine of the Visaragas. Even the munis, on seeing it, became perplexed, how much more the (ordinary) men. For those beasts of Visaragas, who are full of self-consciousness, there is deliverance (only) in subsequent forms of existence, not in this (present) one. Therefore the doctrine of the Visaragas must not be followed. Some Visaragas, striving to unite the individual soul with the All-soul through mortificating the body, others through muttering mantras, others through any meditation whichever, others through any syllable whichever, others through suppression of the breath, fix (it is true) their thoughts on it, but they do not (earnestly) strive for the union with the All-soul. They say that he is in the heart itself; some of them seek for deliverance, considering that no meditation is required, others that the union must be brought about by performing the religious acts as they are described. For these beasts of Visaragas there is (only) deliverance in subsequent forms of existence, not in this present one. He who longs for deliverance in this (present) existence should not follow the doctrine of the Visaragas.
My question is, who are these Visaraga Yogis that are criticized in the Vaikhanasa Dharma Sutras?
Now the passage says that the the doctrine of the Visaraga Yogis was created by Prajapati in order to deceive people. I assume Prajapati is a reference to Brahma, so my first thought was that this is a description of Patanjali Yoga, aka Ashtanga Yoga, since Patanjali's Yoga school was founded by Brahma. It would be understandable for Vaikhanasss to criticize Patanjali's Yoga school, since like most Hindus Vaikhanasas belong to the Vedanta school. Now the Vaikhanasa Dharma Sutras do indeed speak negatively of Ashtanga Yoga, but Ashtanga Yoga is classified as a subcategory of the Saranga Yogis, not the Visaraga Yogis. So "Visaraga Yogis" must be referred to something else.
So does anyone have any idea what sect or school of philosophy is being criticized here?