It appears that "The Batman" counts seasons in 13 episode arcs. Not from September to May. Season 1 ended with the two-parter "Rubberface Face of Comedy" and "Clayface of Tragedy" in which the Joker's modified Joker gas turned Bruce's old friend, Detective Ethan Bennett, into Clayface.
Season 2 ends with the introduction of Commisioner Gordon in "Night and the City." Gordon takes the price off Batman's head, as it were, and chooses to work with the Dark Knight instead of against him to make Gotham a safe place for Barbara Gordon to grow up.
Between Season 2 and 3 is the movie length "Batman v. Dracula" shown on Cartoon Network.
Season 3 introduced Batgirl.
The final episode of Season 3 will repeat on the CW network.
Season 4 begins Saturday, Sept 23. The last I heard, The Batman will air at 11:30 am ET following the Legion of Super Heros at 11:00.
The first episode of Season 4 is "A Matter of Family."
Kevin Conroy (Batman from JLU, Batman:TAS, and Batman Beyond) is voicing John Grayson and Mark Hamill (The Joker) is voicing Tony Zucco.
Dick Grayson/Robin is voiced by child actor, Evan Sabara (twin brother of Daryl Sabara (Spy Kids)).