Hi there Lopsa. The procedure for ban appeals is that the moderator who banned the player will review and reply to their appeal. The reason for this is that the moderator who banned the player would have the most information about the ban since they carried out the warnings prior to the ban. They observed the player's actions and can give the most detailed explanation for banning that player. They may choose to deny, appeal or reduce the ban based on the reasons given in the player's appeal and the circumstances around the ban.
There are some cases where higher staff review is needed. Usually for bans that are unjust or invalid. Other than that it's completely up to the moderator to make the decision on the appeal.