I’ve made a few >1.00 point blunders. Some were oversights where the best checker move was obvious (like this one appears to be), but most were big cube errors (e.g., taking when opponent was too good or dropping as a favorite in a weird/complex/unfamiliar position). IIRC in one example I had about 5 checkers off, 2 got hit, and my opponent was trying to contain them, and I passed as like a 60-40 favorite, but I had no clue what my winning chances were over the board. The error magnitudes can also get amplified at uneven scores.