Pillagers float up after being hit

So when making a dungeon and messing with what mobs to add, i found pillager and was thinking this might be a good common fodder mob. I summoned him and looked at him just to see what he looked like. Then i try to kill him. I hit him with a diamond sword and he disapeared. So i go above ground to mess with the Pillagers a little more and whenever they are hit they seem to just float up into the sky. This seems to be a bug because i can not find anything about them being normal when they float up