This happens if you're switching maps while TvT ends. You only get the "End of Match" buff if you're in the map.
I might fix it eventually, but it's low priority - you can't do a whole lot, since the buff also makes all other players invulnerable. I might make the relic invulnerable as a "quick fix", so someone getting into the map like that cannot warp everyone else out by destroying the relic.