We hope you are enjoying the x2 EXP-Event and are staying safe. Unfortunately we have noticed recently a lot of people using level 1 characters to gain more exp when killing monsters due to a known bug we have within the game. We didn't consider this a rule violation before but after discussing it further with our team, and from seeing the amount of level 1 characters being used to exploit this advantage increase nowadays, this will no longer be allowed and will be considered a general rule violation.
The reasoning behind this is simply, the case of purposely exploiting a bug was never intended to allow parties to gain an EXP advantage.
Thank you for your understanding.