welcome to the forum,
that has been discussed a number of times in the forum,
https://forum.rclone.org/t/megasync-2fa-needed/28792
https://forum.rclone.org/t/mega-multifactor-authentication/27217
and there is already an open issue at github, best to post there.
https://github.com/rclone/rclone/issues/3165