I went on Islamq&a, and it lists a hadith where the gist of it was that the Prophet (ﷺ)'s parents will be in the hellfire, is it true?
That hadith is a matter of controversy among scholars. Among scholars who refused to take that hadith literally and believed that the Prophet’s parents PBUH are not in the Hellfire are Abu Ḥanīfa, al-Rāzī, Ibn al-ʿArabi al-Mālikī, al-Qurṭubī, Ibn al-Jawzī, al-Alūsī, Ibn Ḥajar al-Haytamī, Malā ʿAlī al-Qārī and Ibn Ḥajar al-ʿAsqalāni.
The Egyptian Fatwa Authority issued a fatwa saying that believing the Prophet’s parents to be in Paradise is the stronger opinion. Hadith critics also considered this hadith to be shādhdh (strange and unusual) and therefore refused to take it seriously.
I conducted a study of all of the existing chains of the hadith, which is shown below:
According to the mathematical hadith verification method (see my essay here), this hadith has an authenticity score of 20.5%, which is below the 30% needed for considering it ṣaḥīḥ (authentic). Any hadith that falls below 30% is not strong enough to be used as proof, especially in matters of controversy.
Therefore the verdict is that the view that the Prophet’s parents PBUH are in the Hellfire is not a strongly-supported view and should not be believed in, especially since it goes against important principles of Islamic theology (that those who do not receive revelation are not held accountable), and since many important scholars rejected the view.