I mean Kevin Feige called the the last two phases a "reset" of the MCU at a convention as I recall.
That still doesn't make it a reboot. The whole point of a reboot is about minimizing or outright eliminating narrative connections to previous stories.
I guess Phase 4 could be considered a reset of sorts ("reset" is not exactly a commonly used term for any kind of narrative convention, as far as I'm aware), since it's the start of a new saga with a beginning, middle, and end of its own, but that doesn't make it a soft reboot in the sense that people typically use the term soft reboot for. Like, take Loki, the entire story is the direct result of a very context specific event in Endgame (when Loki stole the tesseract in the past). WandaVision is about Wanda coping with Vision's death in Infinity War, with a side order of her coping with Quicksilver's death in AoU. Also features the return of Darcy and Monica Rambeau from Thor 2 and Captain Marvel respectively, and directly shows the latter's experience when she was restored to life at the end of the Blip in Endgame. Spider-man NWH's plot kicks off as a direct result of Mysterio revealing Peter's identity in FFA, and hinges on Peter knowing Dr. Strange from Infinity War. Thor 4 starts with Thor adventuring with the GotG and then focuses on the return of Jane who was last seen in Thor 2, and how she restores and controls the hammer that was shattered in Thor 3, and gains the powers of Thor due to an incantation that was made by Odin in Thor 1. Shang Chi features the return of Trevor Slattery from Iron Man 3, the Ten Rings organization that was first introduced in Iron Man 1, and the real Mandarin who was first teased in All the King, as well as features Abomination and Wong in a random appearance that starts a plot thread that is continued in She-Hulk.
I could go on, almost every phase 4 and 5 project connects heavily to Phase 1-3. That's the exact opposite of a reboot.
Whereas, presumably, Secret Wars could lead to a true soft reboot if it ends up abolishing old continuity in some way. My guess is that the incursion will create a new universe that maintains some elements of MCU continuity while changing others, and that we will be gradually introduced to what's changed and what's still the same in a way that assumes you've never watched phases 1 through 6. That would be an actual soft reboot.