What exactly is wrong with Irish or Italians specifically converting to Protestantism?

[100% pro-life no matter what]

Contrary to popular belief, there are more Protestants of Irish heritage in the US than there are Catholics of Irish heritage.  Just under half of Irish-Americans identify as Protestant, while only about a third consider themselves Catholic.  It's much closer if you ask whether they were raised Protestant or Catholic.

https://religionnews.com/2014/03/17/irish-americans-religion-politics/

[100% pro-life no matter what]

Tbh it seems to me that the notion that religion is a personal choice is something that in and of itself is essentially Protestant and American. If you go to most other places in the world to be Catholic, Jewish, Hindu, Zoroastrian and probably countless other things is a part of your cultural heritage and identity. I think that a lot of people would see converting to Protestantism as a form of cultural genocide.

Conversion to Protestantism is extremely common everywhere in the Western Hemisphere.

And here's even an example outside it:
https://www.france24.com/en/20191023-iraqi-kurds-turn-to-zoroastrianism-as-faith-identity-entwine
https://syrianobserver.com/features/51332/kurds-embrace-christianity-and-kobani-celebrates-inauguration-of-church.html

Also, Protestant churches are growing very quickly in Latin America.  Lots of places that were uniformly Catholic a generation ago are now like 20-40% evangelical Protestant.