In-game bans, initially, may not have proof attached. If you submit an appeal, the banning admin will reply and attach the proof if they haven't already done so. If you receive no response to appeal within 72 hours (3 days), you can submit a Feedback ticket to Game Mod Management regarding the ban.
Ban appeals can be filed here - https://truckersmp.com/appeals
Feedback can be submitted here - https://truckersmp.com/feedback