Primarily, you have an outstanding amount of recent punishments - 7. This final instance after your string of rulebreaks - you mass rdming, should've made your ban lengthier than even 4 days.
To learn and improve your attitude for the future, take this time to re-read the server rules and know that your entities are your responsibility (such as a C4 or nitro). It's also a good idea to not use special weapons where it can affect other people. Lastly, expect a much longer and less lenient ban if you come unbanned and do something like this again.