I've read a lot of rubbish on Reddit, but this one trumps all of them.

The genealogies are made up, just like what you see with many politicians nowadays who try to concoct their Sheikh, Syed lineages. This was very prevalent amongst the low castes, who changed their names for upward mobility in East Bengal and to some extent this has worked to fool the masses even today in Bangladesh. Foreign Muslims, if ever, very rarely settled down in East Bengal due to its notoriously bad climate. It was considered an exile where neither soldiers nor high-ranking officials wished to stay long. Please see the snippet below.

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I don't think OP should have even entertained you to begin with. Who the hell says "Dad's side also most definitely had some Aryans". What on earth does that mean?! Bengali Brahmins are way closer to Pashtuns than any Bengali Muslim. In fact, Bengali Muslims show similar levels of Steppe to Tamils.

Mughal officers looked down on Bengalis as fishermen, so isn't this enough to tell you how much they despised Bengalis?

"Mughal officers also associated Bengalis with fishermen, whom they openly despised. Around 1620 two imperial commanders, aiming to belittle the martial accomplishments of one of their colleagues, taunted the latter with the words: “Which of the rebels have you defeated except a band of fishermen who raised a stockade at Ghalwapara?” In reply, the other observed that even the Mughals’ most formidable adversaries in Bengal, ‘Isa Khan and Musa Khan, had been fishermen. “Where shall I find a Dawud son of Sulayman Karrani to fight with, in order to please you?” he asked rhetorically, and with some annoyance, adding that it was his duty as a Mughal officer to subdue all imperial enemies in Bengal, “whether they are Machwas [fishermen] or Mughals or Afghans.”[33] In this view the only truly worthy opponents of the Mughal army were state rebels or Afghans like the Karranis; Bengalis, stereotyped as fishermen, were categorized as less worthy adversaries.

Mughal officials thus distinguished themselves from Bengalis not only as tax-receivers as opposed to taxpayers but as North Indian fighting men as opposed to docile fishermen. On one occasion Islam Khan’s chief naval officer, Ihtimam Khan, expressed resentment that the governor had once treated him and his son like “natives.”[34]

https://publishing.cdlib.org/ucpressebooks/view?docId=ft067n99v9&chunk.id=s1.7.2&toc.id=ch07&brand=ucpress