^ Anecdotally I believe it occurs in a much lower amount, I haven't seen it at all as an Indian Muslim.

Just read the oppression Indian lower caste untouchable Muslims face in India.

https://en.wikipedia.org/wiki/Pasmanda_Muslim_Mahaz

Upper caste dominant ashraf/sayeed Muslims in India have tried to label the people of the Mahaz as "un-Islamic heretics", which is a form of propaganda against them. Same is the case in Pakistan.

We all are Muslims and we don't have castes. Unless it's about an upper-caste Muslim woman marrying a lower caste untouchable muslim.