Tafsir of Ya seen 36:10

This means: your warning them and the absence thereof are equivalent to them, according to the verification that has already passed in the beginning of Surah al-Baqarah. The manifest [interpretation] is that the conjunction is linked to { Indeed, We have placed... }, as if it were brought forth to explicitly state what they are upon in their own selves, following the indication of it in what preceded, based on the fact that it is something that entails the aforementioned "placing" (Ja'l).

A view similar to this is that what preceded was to explain their state as a result of that "placing," while this is to explain their state without considering the "placing," and it serves as a preparation for His saying, the Exalted: { You can only warn... }, etc. In Irshad al-'Aql al-Salim, it is stated that it is an explanation of their condition by way of explicit statement, following its explanation by way of parable. In al-Hawashi al-Khafaji, it is noted that the letter fa (so) was not brought with it despite its consequence to what preceded, either to leave it to the listener's mind or because it is not intended here; the end.

Observe whether you find any impediment to it being a conjunction to { they do not see }, so that it may also be a predicate for them, entering into the scope of the fa and the deduction from what preceded, as if it were said: "So it is all the same for them..." etc. The difference between the two sentences in nominality and verbality is not something I believe you would consider an impediment.

His saying, the Exalted: { they do not believe } is an incipience (istinaf) that confirms what preceded it, clarifying the ambiguity regarding the state of equivalence contained within it, or it is a confirming state (hal), or a substitute (badal) for it.