I’ve watched and read a lot of what people think happened to Ahsoka during this epsiode. That she went to the World Between Worlds and confronted Anakin.
But I have a different take on this. SPOILERS FOLLOW!
When Ahsoka sees Shin Hati return to the the map matrix without Sabine, she succumbs to the fear that Sabine is dead. Fear leads to hate and she responds with rage, using the Force to pick up Shin and smash her into the rocky crag. After years of stoicism, this sudden dip toward the Dark Side unbalanced her, leaving her vulnerable to Baylon’s attack which knocked her off the cliff. When she awakes, she seems to be in the World Between Worlds and hears her former Master calling her. She turns to see Anakin Skywalker, and in the next episode, he tells her her is going to complete her training. She battles him briefly, then she relives the Battle Of Mandalore, before battling him as Anakin and then as Vader, red lightsaber and all. When she defeats him, she declines killing him and tells him she has decided to live.
My take on this: She was never in the World Between Worlds. I think she was in the ocean, probably wrapped in a Force Bubble, and was having an internal struggle with her guilt over leaving Anakin, over all the death and destruction for which she felt responsible, and for losing control, even for just that moment. Seeing Shin return without Sabine triggered a moment of fear — and fear leads to hate so she responded with a sudden surge of rage, smashing Shin into the rocky crag. This momentary slide toward the Dark Side, after years of stoicism, unbalanced her, leaving her open to Baylon’s attack. The latter, along with Baylon’s comment that her entire legacy was death and destruction, triggered this introspection, leading to an epiphany, that she wasn’t responsible for Anakin’s fall and that she could choose how to proceed with her life. Jacen, being Force-sensitive, could hear this and Hera was picking it up from him.
That’s my view of the events. Let me know what you think.