I have to disagree that it's racist and anti-Catholic for someone to assert that "aitch" is the only correct way to pronounce the letter h.
Even in GB, "haitch" is far more common amongst young people than "aitch". The British Library noted this change in 2010. In a few more decades, haitch will be the more established common pronunciation.
It is this perceived change in pronunciation I think dome are responding to, often under impression that "aitch" was always correct when it originally wasn't. Seems to me this is the more likely explanation.
Indeed, this article by the Independent in 2018 states:
"Shibboleths die hard – the opprobrium in Australia attached to haitch probably derives from its long association with Irish Catholic education. There’s no real evidence for this, mind, as Sue Butler points out, but never let facts get in the way of a good shibboleth."
www.independent.co.uk/news/long_reads/haitch-or-aitch-pronunciation-letter-h-old-english-a8393766.html
But there's no real evidence opposition to "haitch" is based on anti-Catholic and anti-Irish racism.
Having said that, the article linked makes a very good case for pronunciating h as "haitch" which many posters here will like.
One of the main benefits is children learn how to spell with "haitch" much better than with "aitch". Pronounce as you spell is definitely helpful.
I wouldn't be at all surprised if the same people rail against the changing pronunciation of "mischievous" too.
Interestingly, while North America retained the "haitch", they never added the h back into their pronunciation of "herb".
The word "humble" was a French word that entered English without an h. It was the English who added h into "humble" as well as "hat".
So, it would be pretty odd for any English language speaker to seriously object to "haitch" instead of "aitch". 🤷♂️