"All-time top-ten market creators" are defined by this link:

https://manifold.markets/leaderboards

"Banned" means they show a little "Banned" flag next to their name on the user page, like this.

It counts if they get banned even for a short time during the year -- provided someone screenshots it and posts in the comments. (They need to be banned and top-ten at the same time for it to count.)

If it happened in the past (i.e. before 17 Feb. 2023) it doesn't count. (It appears that none of the present top-10 are presently banned.)