1. Using VPN : Using VPN changes the IP address of your computer, changing the server for VPN again and again will change the IP and thus the omegle may suspect you as a robot or someone trying to load their server traffic and thus their algorithm banns it.
2. Leaving the account logged in : Sometimes when we shut a laptop from a friends house or another computer in house we leave the account logged in and thus if the account is logged in more then 5-6 times the server may think that the account is being used by someone else and thus banns it.