Remember that, though the potato crop was devastated by blight, there was always enough food in Ireland to feed the people. The people simply could not afford to buy the food at the prices that Britain insisted they pay. The British were more concerned that the Irish people would get something without paying than they were about Irish people starving to death.

Don't forget that the British also blockaded food aid from the Ottomans to Dublin, increased evictions, and mandated export of all staples except potatoes.... While also mandating that only the Irish Lumper variety be grown. A particularly bland and flaky type of potato, and highly susceptible to disease, it's only saving graces being size and starch content