In my survival world, twice I have started a raid, and about half way through I exit my game, and return at a later date (day the next day), and immediately the bossbar says "raid Defeat", despite all my villagers being alive. To emulate, start a raid, complete 2 waves of it (not sure if it is necessary, but whn I emulated it that's what I did), then exit and save the world, close Minecraft, open it up again, and go in the world.