hey flash!
the cooldown system has been implented some time ago but since you're new you're probably not familiar with it.
you get a cooldown every time you do not join the game in time / leave the game / rep yourself and don't wait for the sub. on offclass disabled lobbies, you can get an offclass cooldown for offclassing for a long time. each time you get a cooldown, it has a level. you can check the levels on https://tf2center.com/rules#6_2 . unfortunately, the tool is not perfect, so the cooldowns can be unfair sometimes. when that happens, feel free to message the tf2c staff (Pitts, Warpy , Bluebunny) on tf2c main chat or dm me on discord (Pitts#6139) and we'll remove the ban for you .
having cooldowns on your record don't really affect you that much, unless it's offclassing cooldowns, so don't worry about it