The Quran informs us that Muhammad did not have a physical miracle.
[10:20] They say, “How come no miracle came down to him from his Lord?” Say, “The future belongs to GOD; so wait, and I am waiting along with you.”
(٢٠) وَيَقُولُونَ لَوْلَا أُنْزِلَ عَلَيْهِ آيَةٌ مِنْ رَبِّهِ فَقُلْ إِنَّمَا الْغَيْبُ لِلَّهِ فَانْتَظِرُوا إِنِّي مَعَكُمْ مِنَ الْمُنْتَظِرِينَ
The Quran informs us that God stopped sending the kind of physical miracles that were sent in the past.
[17:59] What stopped us from sending the miracles is that the previous generations have rejected them. For example, we showed Thamûd the camel, a profound (miracle), but they transgressed against it. We sent the miracles only to instill reverence. (٥٩) وَمَا مَنَعَنَا أَنْ نُرْسِلَ بِالْآيَاتِ إِلَّا أَنْ كَذَّبَ بِهَا الْأَوَّلُونَ وَآتَيْنَا ثَمُودَ النَّاقَةَ مُبْصِرَةً فَظَلَمُوا بِهَا وَمَا نُرْسِلُ بِالْآيَاتِ إِلَّا تَخْوِيفًا
The Quran also informs us that Muhammad’s only miracle was the Quran.
[29:50] They said, “If only miracles could come down to him from his Lord!” Say, “All miracles come only from GOD; I am no more than a manifest warner.” [29:51] Is it not enough of a miracle that we sent down to you this book, being recited to them? This is indeed a mercy and a reminder for people who believe.
(٥٠) وَقَالُوا لَوْلَا أُنْزِلَ عَلَيْهِ آيَاتٌ مِنْ رَبِّهِ قُلْ إِنَّمَا الْآيَاتُ عِنْدَ اللَّهِ وَإِنَّمَا أَنَا نَذِيرٌ مُبِينٌ (٥١) أَوَلَمْ يَكْفِهِمْ أَنَّا أَنْزَلْنَا عَلَيْكَ الْكِتَابَ يُتْلَىٰ عَلَيْهِمْ إِنَّ فِي ذَٰلِكَ لَرَحْمَةً وَذِكْرَىٰ لِقَوْمٍ يُؤْمِنُونَ
If Muhammad could produce the Quran despite being illiterate, that would contradict the above verses and signify that Muhammad received a physical miracle beyond the Quran.
Taken from: https://qurantalk.gitbook.io/muhammad-was-not-illiterate/muhammad-did-not-have-a-physical-miracle