That's according to documents that have emerged from the ongoing case between Microsoft and the Federal Trade Commission over the former's attempt to acquire Activision Blizzard, which have been shared by The Verge. It looks to be a presentation, with the slide in question being titled "Microsoft's approach following acquisitions since 2018". It includes a handful of Bethesda's games that have been released since 2014, their available platforms and quotes pulled from various interviews regarding exclusivity.
The entry for The Elder Scrolls 6 has its release date as "TBC, but expected 2026 or later," and the entry for available platforms is notably missing any mention of PlayStation. The quote is pulled from an interview Phil Spencer did with GQ in late 2021, where he says: "In order to be on Xbox, I want us to be able to bring the full complete package of what we have. And that would be true when I think about Elder Scrolls 6."
The document lines up pretty well with what we already know: That The Elder Scrolls 6 is still a ways off. The 2026 release date was brought up back in June when a Microsoft lawyer fumbled and said that "Elder Scrolls 16" was projected for release that year which, unless there are a further 10 entries in the works for the next three years, I think we can safely assume was supposed to refer to The Elder Scrolls 6.
Even back when the game was announced at E3 2018—a gun jump that Todd Howard regrets in hindsight—we were warned that it was still a very, very long way away. Howard said it was "good to think of The Elder Scrolls 6 as still being in a design [phase]" back in 2021, before finally revealing that it had managed to crawl its way out of pre-production in August.
The document also seems to confirm what PlayStation Bethesda fans have long feared, that the game won't be making its way over to the console. While it's never been explicitly stated by Spencer or Howard that this is the case, recent history with Redfall and Starfield's release largely pointed towards a similar fate for The Elder Scrolls 6. It's a darn shame, though I suppose there's at least three years to save up for a console. Who knows, maybe the next generation will be out before we see Tamriel once more. Or just get it on PC, because we all know that's going to be the best version.