I've also seen "data point" used when a singular form is required. I think in common usage, "data" is a mass noun like "mayonnaise" rather than a plural.
This applies to the singulars that denote single objects too: scissor lift, pant leg; not scissors lift or pants leg.
According to this principle, it should be datum point, where only the head noun point may be pluralized.
"Datum point" exists, but I've never seen or heard it in use; it's just a "confirm by Google".
Were you also commenting on its pronunciation? I'd instead say: "data" is a mass noun like "mahyonnaise" and "tomahto sauce".