The account was stolen . Accounts recently stolen are more likely to be restored by the owner or stop working and you losing the account. Its recommended to buy a safer more older account. Read our recommendations.
Email Change
Supercell often doesnt let you change email from a new device.
Owner may still be logged in!
Supercell doesn't log users out, it's possible the owner can still be logged in and play on the account at the same time.