According to Mark, some people testified that Jesus had said he was going to rebuild the temple in three days. Matthew has them saying something similar, though in that version of the story they just accuse Jesus of saying he’s able to do it. The gospels describe these statements as “false testimony” or “false evidence” from “false witnesses”.
But according to John, Jesus did in fact say he would raise the temple again in three days. (Or maybe just that he could do it. Either way, one of those other gospels is wrong about it being false testimony.)
There was another thing included in the allegedly false testimony. The gospels said the people said Jesus said he would/could destroy the temple and rebuild it in three days. Maybe when the gospels called that testimony false, they just meant the part where people accused Jesus of planning to destroy the temple himself.
But even that part might not really be false. Matthew indicates that when Jesus talked about the destruction of the temple, his disciples assumed he was saying it would be his doing, and Jesus didn’t argue with that…