In some cases, when you are pressing a key (in my example Key: 'A'), so that you go to left; and you're player switching the server, for example, thru a bungeecord or something similar (in my example: Hypixel-Game -> Hypixel-Lobby), it can be stuck with the key, without pressing it, after the server-switch/reconnect, so that you walk left infinite. (Until you press the actual key again)