My first assumption was that the episodes went up early by mistake, but the series page does have a "season finale now streaming" notice on it, so maybe this early release was intentional?

source: www.dohtem.com/bugs/news/

Continuing to air new episodes weekly:

"ADVENTURE TIME: FIONNA AND CAKE" every Thursday

#AdventureTime

"AZTEC BATMAN: CLASH OF EMPIRES" is coming to HBO Max on December 22! #DC

"NE ZHA II" is coming to HBO Max on December 20!

"ADULT SWIM'S THE ELEPHANT" is coming to HBO Max on December 20! #AdultSwim

Season 9F of "TEEN TITANS GO!" is coming to HBO Max on December 19! #CartoonNetwork #DC

Season 1D of "TOAD AND FRIENDS" is coming to HBO Max on December 14!

Season 2I of "BUGS BUNNY BUILDERS" is coming to HBO Max on December 9! #Cartoonito #LooneyTunes

Season 3A of "BATWHEELS" is coming to HBO Max on December 5! #Cartoonito #DC

Season 1D of "DYLAN'S PLAYTIME ADVENTURES" premieres on HBO Max on December 4!

"NE ZHA" is coming to HBO Max on December 1!

GKIDS animated films coming to HBO Max on December 1:

Liz and the Blue Bird
Lu Over the Wall
Millennium Actress
Mind Game
Perfect Blue
Summer Wars
The Colors Within
The Girl Who Leapt Through Time
Wolf Children