The other player had the small bets. You are right that the strange numbers are a sign of automated arbitrage. That’s speculation. The other thing is no other book would confiscate money under the same circumstances. This is text book sharp action where the odds provider automatically limits and makes the book aware. As I’ve said, XYes has two bets playing both sides or they don’t. If they don’t then the player should be paid in full.
Strange numbers have nothing to do with arbitrage. It is just clicking the max button and then betting whatever is shown there.
In fact it's more a sign of NOT arbitrage betting because anyone doing arbitrage would be smart enough to not bet the full max.