I don’t know, it’s not even that, although that is noticeable.
To me, the character of Ahsoka in TCW grappled with a lot of different themes and developed through them genuinely pretty interestingly: The gradual breakdown of an upbringing she romanticized, learning to roll with those punches, and adapt her teachings in increasingly less black and white scenarios, eventually leading to a disillusionment of the larger system, and her trying to rediscover trust in its base ideologies… She went through a lot, and grew from it.
She was Anakin Skywalker’s padawan, and his influence - good and bad - reflected in her choices. But she was still her own person, overcoming some of his failures and falling short of some of his successes. She was three dimensional and endearing; young but quickly maturing.
Put her through betrayal and a genocide of everyone she’d ever known, forced to hide from an Empire, and you’d think there would be a lot to unpack for a complex character like her. But Rebels just treated her as fanservice and a plot device. She shows up as a moment of relief: “Look! It’s that character you love!” and serves as a reassuring presence to the audience proxy of Ezra from time to time. She’s a wise and matronly mentor. Obviously all that hardship and strife just made her a stronger and better person. That’s such a boring cop-out catch-up. And now she’s just there. Sad about Vader, but still.
Whether or not she was snippy in Rebels, she was too perfect, so to speak. I would have wanted more from her disavowment of the Jedi, not just the vague “something else” that was never elaborated on. And surely that lack of commitment to those philosophies would have opened her up more to the grief she must feel for what she’s lost. Especially in light of the complicated relationship she had to it anyway. Something more along the lines of where Kanan was.
My hopes or headcanon for her going forward, is that they’ll finally lean into the elements that made Ahsoka interesting. That she only came off as boring in Rebels because we were tied to a young Ezra’s POV. And maybe that’s true, if she is showing up only halfway through season 2 of The Mandalorian. She’s not a Jedi, maybe they’ll finally elaborate.
And further into hopes for the larger canon, I’m a fan of the idea that she maybe doesn’t help Luke build the New Jedi Order. I would honestly like if they cast her in an antagonistic role at some point. Not as a villain villain, but someone opposed to rebuilding the Jedi in the way it was. And that could tie into TLJ, where Luke is disillusioned himself.