Mike Lindell, the MyPillow founder and Trump ally who has been a leading voice in pushing conspiracy theories about the 2020 presidential election, must pay $5 million to a software forensics expert who debunked a series of false claims as part of a “Prove Mike Wrong” contest, an arbitration panel said on Wednesday. Mr. Lindell had issued the challenge at a “cyber symposium” in South Dakota in 2021, saying he had data that would support his claims that there was Chinese interference in the election and offering the seven-figure prize to anyone who could prove the data had no connection...