You have been outbid by a previous bidder's bid, and $2.50 is the bid increment.
At any given time, the showing bid amount is one increment or less above the second highest bidder's maximum bid amount, up to the high bidder's maximum bid. eBay only displays enough of the high bidder's maximum bid to take the lead by up to one bid increment.
eburtonlab
Mentor1 year ago@pegy49
You have been outbid by a previous bidder's bid, and $2.50 is the bid increment.
At any given time, the showing bid amount is one increment or less above the second highest bidder's maximum bid amount, up to the high bidder's maximum bid. eBay only displays enough of the high bidder's maximum bid to take the lead by up to one bid increment.
https://www.ebay.com/help/buying/bidding/automatic-bidding?id=4014