Blockstream's Liquid sidechain has been paused since Sunday, after about 4,000 BTC worth roughly $320 million left the federation wallet that backs every L-BTC in circulation. SideSwap, a federation member running a peg-out service, said a customer sent it 4,000 L-BTC at 14:05 UTC. It burned them under a valid authorization, and 23 minutes later the federation paid out 3,996 BTC.