I wont try and justify what Cromwell did, although I will point out that the Irish then and now exaggerate the death toll of 1649-50, and indentured servitude of prisoners of war was commonplace in Europe. Cromwell also took masses of Scottish Royalists as ‘slaves’. Ironically his army was not English, but an amalgam of English, Welsh and Ulster Scots, perhaps even a few Scots.
I would also remind people that any Cromwellian hate had its roots in the famous 1641 uprising, where the Irish Catholics slaughtered thousands of Protestant English and Scottish settlers, inc women and children.
To diminish the magnitude of what happened to the Irish under English rule is quite disingenuous.