Spoilers please. Huge fan of Clone Wars, never really got into Rebels
The bare-bones of it is Ezra resists the Emperor's temptations, the rest of the crew activates the planetary shields to deflect bombardment by Thrawn's fleet. Ezra fights his way to the bridge of Thrawn's ship as the Purgill, whom Ezra called for help, decimate the Imperial Fleet. The Purgill grab Thrawn's ship, destroy the bridge and take the ship to the Unknown Regions.
Flash foward 10 years. The rest of the crew remained to fight in the Rebellion. Hera, Sabine, Rex at all fought at Endor (you see the
Ghost at the battle of Scariff in
Rogue One). With the war over, Sabine realizes that Ezra's sacrifice wasn't just one-sided and she and Ashoka Tano leave for the Unknown Regions to search for Ezra and bring him back to the planet he gave up everything to save.
It establishes going into the new Trilogy that Ezra is still likely alive, Sabine alive, and more importantly Ashoka Tano is alive; a very powerful force user. Ezra and Sabine are both young and would only be in their early 50s by
Force Awakens. Prime candidates to be Rey's parents.
From IndieWire:
Ezra’s Double Sacrifice
In the finale, Ezra is tested when a disguised Palpatine (Ian Diarmid returns) tempts him with a happier alternate life, one in which his parents are still alive and waiting to welcome him. Knowing that his fellow rebels need him, Ezra turns his back on the tantalizing image, thus causing Palpatine to reveal his true face.
“Ezra has seen him as evil and so evil has to be deceptive too,” said Filoni. “To challenge Ezra, he appears as this pleasant person [appears as he does prior to his duel with Mace Windu]. You can figure out technically how he does that with old holograms or whatever. What’s important is this is, this is the way he deceives you: Oh look, he’s not so bad. He’s this kindly old grandfather-looking guy, and that makes you want to trust him a little more, trust a little more.
“The whole trick there is that the emperor hears what Ezra desires most in the world between worlds. When he says, ‘Sometimes I wish my life was different. Sometimes I wish I could just be with my mom and dad,’ because when you’re pressed into difficult choices, your gut reaction is not wrong… That’s just the burden of being a hero and you have to be careful [if] that wish is given or granted to you.”
He also knew that in working with the Purrgil, he would have to stay with them when they left, and that left his friends unsure about his ultimate fate. Giving up the family he’d built for himself was no small sacrifice.
[Ezra smashes the windows on the bridge of Grand Admiral Thrawn's star-destroyer as the Purgill grab the ship and jump into hyperspace, killing Thrawn and everyone else present presumably]
People were never going to like these new movies no matter what, IMO. Star Wars is just too close to a lot of people. Spin offs like Rogue One that don't fuck with old beloved characters are gonna fare fine as long as they are decent, but Ep 7, 8, and 9 were never gonna be well received. Everyone has this "vision" for what these movies were gonna look like and few if any people were going to have that matched.