Ahsoka has a very fair share of mistakes, failings, and situations she needed to be rescued from in the series.
Season 1: She placed her trust in R3, she got trapped in the cell by Ventress and Gunray and needed to be rescued by Luminara, she got infected with the blue shadow virus and needed to be rescued by Anakin and Obi-Wan, and she got her entire squadron killed in the same episode she whipped out that Thrawn tactic.
Season 2: In hubris she didn't fall back and got a great number of her forces killed on felucia and was punished by the Jedi council, in naïveté she got captured by Cad Bane and used as leverage against Anakin, she lost her lightsaber and had to spend an entire episode getting back and learning the importance of patience, she lacked subtlety when she and Koon were checking out drinking holes.
Season 3: Ahsoka got outsmarted and captured by mandalorians, Ahsoka screwed up with her visions and had an embarassing false alarm, Ahsoka got shot and needed to be rescued by Padme, she doesn't understand that the sides of the war aren't black and white and needs to spend an episode learning it, Ahsoka got captured and used as the Son's hostage/weapon prior to being killed and needing to be resurrected, Ahsoka got captured on the battlefield by Trandoshans.
Season 4: Ahsoka and the other Jedi got humbled by their capture on Kadavo.
Season 5: Ahsoka struggled with her feelings for Lux, got shot and failed to save Steela, got captured by pirates and needed to be rescued, got completely used and manipulated by Barriss, and got captured and almost executed.
She's hardly some perfect character with an answer to every dire circumstance, and that's the point. Ahsoka's imperfect, she grows and learns from her failures, that's kinda the point of her entire character arc and why she's one of the most dynamic characters in TCW.
Sure she rescues other characters quite a bit of the time but she has her own fair share of times when she herself needs to be rescued.
Calling Ahsoka a Mary Sue makes no sense.