sniper

SNIPER noun

[ C ] uk/ˈsnaɪpər/ us
someone who shoots at people from a place they cannot see

снайпер on a website, someone who makes an offer for an item just before the end of an auction (= a sale in which things are sold to the person who offers the most money)

человек, перебивающий сделку перед самым окончанием аукциона