Why is there a series that has a date and there is not? And how to remove it if possible

When editing and saving a series on its /editgame page, this date gets added. Where site staff sadly can't remove it. So it's better to edit a series on its /editseries page instead.

There are two different edit pages due to the site redesign, where all Teams, Marathons, and Series were all kinda merged into a game.

E.g., I have a verified run in the Hypixel series: https://www.speedrun.com/hypixel/run/ydggpxjy

Where that series' game leaderboard can be seen on this URL: https://www.speedrun.com/hypixel/full_game