There are a number of reasons why you could have gotten banned from Omegle.
Strangers that you have been matched with “drop” you regularly. This will make Omegle take notice and it will be considered suspicious.
You may have offended someone and they have consequently reported you. Or else there might be users that like to get people banned and have reported you for no reason at all. Omegle is known to take these reports seriously and quickly ban people without taking the time to investigate.
Unknowingly violating the terms and conditions of the site. This includes any abusive behavior or harassment. You can also get banned for playing copyrighted music or if a TV show is playing in the background while you’re having a conversation.