Pillagers appear to track the player while the former is in creative mode, appearing as if they are primed to attack. The tracking is noticeably different than other hostile mobs simply looking at the player, and it looks even stranger while the pillager is walking.

Note: I don't believe this is a duplicate of MC-146524, as the pillagers do not attack (or even charge their crossbows). Furthermore, this occurs even when loading into a world in creative mode, without switching gamemodes.

Video demonstration here.