There is little point in speculating about what happened. The last-minute buyer could have messaged the seller with a cancellation request. Or the seller may have refused to sell because the price was not high enough. Or they could conceivably even have used another iD to try to pump up the selling price (shill bidding), although doing this so close to the end of the auction would be foolish as they could end up winning their own auction.
The price for which it has been relisted may give you a clue. Just decide whether you still wish to bid for this item - or buy from this selller - and act accordingly.
