At the end of Solo: A Star Wars Story, what appeared to be Darth Maul appeared in a hologram. Does anyone know if that was actually Darth Maul, or was it another Sith that looked exactly like him? If it was him, wouldn't that screw up the timeline, as Maul was killed when Anakin was 8-ish, but would have been alive when Solo was in his early 30s?
Yes, it is the former Sith, Maul.
Many people whom have only ever watched the films do not realize that Darth Maul survived after The Phantom Menace and where he reappears in the TV series, The Clone Wars, and turns up again in the TV series, Star Wars Rebels, which Rebels takes place after Solo: A Star Wars Story and both of those works (Solo & Rebels) takes place inbetween Revenge of the Sith and A New Hope.
At the end of Solo: A Star Wars story, it's revealed Emilia Clarke's Qi'ra has been in contact with fan favorite Star Wars villain, Darth Maul, played once again by Ray Park. If you've only followed the Star Wars movies, your last memory of Darth Maul was seeing him fall to his apparent death after being sliced in two by Obi-Wan Kenobi at the end of Episode I: The Phantom Menace. However, if you've watched the Star Wars: The Clone Wars series, you'd know Darth Maul survived his fight with Obi-Wan. You'd also know he now has robotic metal legs. We have an even more in-depth explanation on where Maul has been and what it means for future Star Wars movies here. Actor Sam Witwer is voicing Maul in Solo, who also provided the character's voice on The Clone Wars show. (FYI on the timeline, which can admittedly get confusing: The Clone Wars series takes place between Episode 2: Attack of the Clones and Episode 3: Revenge of the Sith. Solo: A Star Wars Story takes place some time after Episode 3, but before Episode 4: A New Hope.)
HERE is a breakdown of the timeline.
By this point the old Jedi Master is in self-imposed exile on Tattooine. This is where the revenge driven Sith finally falls. Season 3 of Rebels takes place in 2 BBY. So, if you’ve been doing the math, Solo is 10 years after The Clone Wars: Season 4, 9 years after Revenge of Sith, and 8 years before Rebels: Season 3.