Sheikh Ali Al-Omran, may God preserve him, says: “The illiteracy of Sheikh Al-Islam was published by Brother Khaled Al-Luhaidan
He relied on several late written copies, and he mentioned some of the evidence to support them, although I do not agree with him for certain attributing it to him, but there is a great deal of consideration in it.
Then I found a written copy of it on Tora, in which there are fatwas by Ibn Taymiyyah
The handwriting of one of Ibn Taymiyyah’s cousins, dated (762), is very good and precious, but he did not
It is certain that it is attributed to Sheikh al-Islam, so it remains to gather these evidence and presumptions if we want to be certain whether they are confirmed or denied.