Doctor Who has finally explained a decade-old Dalek mystery from the Time War. Continuity has never exactly been Doctor Who's strong suit, and that's a feature rather than a bug; as Doctor Who author Paul Cornell opined on his personal blog, "Not giving a toss about how it all fits together is one of Doctor Who’s oldest, proudest traditions, a strength of the series... It’s allowed infinite change, and never left the show crunched into a corner after all the dramatic options had already been done. Terrible continuity equals infinitely flexible format."
And yet, occasionally Doctor Who makes a continuity blunder that's just a little too problematic. There are two contradictory versions of the origins of the Daleks, and there have been multiple accounts of their end as well. Most problematic of all is the fate of their homeworld, Skaro, which was destroyed by an ancient Time Lord superweapon called the Hand of Omega in the classic story "Remembrance of the Daleks" — and then mysteriously cropped up again in the relaunched series, referenced in 2010. There was no easy way to explain this because the restored Skaro certainly appeared to be from later in the timeline, well after the Time War.
In February 2021, the BBC published Dalek: Mark III Travel Machine Combat Training Manual, essentially a guide to all things Dalek, which attempts to fix this problem with a brief note. A section discussing "Remembrance of the Daleks" concludes: "NB Study of the timeline of Skaro indicates several temporal anomalies relating to its destruction and subsequent reconstruction that are currently being investigated."
It's important to remember that, in Doctor Who, history is remarkably fluid. While there are some limitations, including so-called "fixed points in time," time travelers like the Doctor essentially have the ability to rewrite history itself. It is impossible for a show about a dimension-hopping time traveler to have a canon," then-writer and future showrunner Steven Moffat remarked at San Diego Comic-Con 2008, hinting the time travel actually creates alternate timelines that viewers have experienced. And the Doctor is not the only time traveler; the Daleks themselves possess time travel technology of sufficient complexity to challenge the Time Lords themselves in the Time War.
This perfectly explains why "Remembrance of the Daleks" can still fit with modern Doctor Who and the restored Skaro. Presumably, the destruction of Skaro was one early shot in the Time War itself, but the Daleks used their own time travel technology to rewrite history and prevent it. This would fit well with the "temporal anomalies" reported in the latest Doctor Who tie-in book, and this particularly continuity wrinkle is therefore ironed out quite neatly.