I don’t think it’s some sort of carefully-manufactured phenomenon. I think that people just generally complain about immigration.

From the article:

Ireland, according to this narrative, has opened the floodgates to foreigners with no controls or checks, leaving rapists and murderers to prowl the streets, and no one – not the government, not opposition parties, not the media, not the police – is taking it seriously.

“People need to fight for this country,” said Samantha, a 27-year-old mother, as masked youths clashed with police attempting to retake Eden Quay along the River Liffey. “I’m not racist; I don’t mind people coming in if they respect Irish people. But the likes of the toerags coming into this country – they’re not vetted and are causing havoc.”

You can put the shoe on the other foot, go back to when there were waves of Irish immigration to the US, and people complained about the Irish then.

https://en.wikipedia.org/wiki/Anti-Irish_sentiment

Nineteenth-century Protestant American “Nativist” discrimination against Irish Catholics reached a peak in the mid-1850s when the Know-Nothing Movement tried to oust Catholics from public office. Henry Winter Davis, an active Know-Nothing, was elected on the new “American Party” ticket to Congress from Maryland. He told Congress that the un-American Irish Catholic immigrants were to blame for the recent election of Democrat James Buchanan as president, stating:

The recent election has developed in an aggravated form every evil against which the American party protested. Foreign allies have decided the government of the country – men naturalized in thousands on the eve of the election. Again in the fierce struggle for supremacy, men have forgotten the ban which the Republic puts on the intrusion of religious influence on the political arena. These influences have brought vast multitudes of foreign-born citizens to the polls, ignorant of American interests, without American feelings, influenced by foreign sympathies, to vote on American affairs; and those votes have, in point of fact, accomplished the present result.

Much of the opposition came from Irish Protestants, as in the 1831 riots in Philadelphia, Pennsylvania.

Protestants of the nineteenth century would use crime statistics to allege that Irish Catholics were over-represented in crime.

During the 1830s in the U.S., riots for control of job sites broke out in rural areas among rival labour teams from different parts of Ireland, and between Irish and local American work teams competing for construction jobs.

Irish Catholics were isolated and marginalized by Protestant society, but the Irish gained control of the Catholic Church from English, French and Germans. Intermarriage between Catholics and Protestants was strongly discouraged by both Protestant ministers and Catholic priests. Catholics, led by the Irish, built a network of parochial schools and colleges, as well as orphanages and hospitals, typically using nuns as an inexpensive work force. They thereby avoided public institutions mostly controlled by Protestants.

The Irish used their base in Tammany Hall (the Democratic Party machine in New York City) to play a role in the New York State legislature. Young Theodore Roosevelt was their chief Republican opponent, and he wrote in his diary that:

There are some twenty five Irish Democrats in the house… They are a stupid, sodden and vicious lot, most of them being equally deficient in brains and virtue. Three or four however…seem to be pretty good men, and among the best members of the house are two Republican farmers named O’neil and Sheehy, the grandsons of Irish immigrants. But the average catholic Irishman of first-generation as represented in this Assembly, is a low, venal, corrupt and unintelligent brute.