EBay uses a form of proxy bidding in which the bidder can confidently bid their maximum, and eBay will update the bidding as more bids come in.
So if the opening is $10 and I bid $100, the bid is to me at $10 only.
But then you bid $15, which seems higher but is still well below my maximum.
The bid is still to me, but to outbid you, it now shows as $16.
You get annoyed and bid $25-- and now it shows me winning at $26.
And so on until one second before the auction ends when @mrdutch1001 swoops in with a $150.15 "snipe" bid and wins at $101.00.
The general advice is bid once and bid your maximum.
And to outwit snipers , bid late.