A recent update notification on Ubisoft's support site indicated that gamers in the UK who pre-ordered collector's editions of Assassin's Creed Valhalla, Watch Dogs: Legion, and Far Cry 6 for Xbox One from the Ubisoft Store will not be getting discs. The post goes on to indicate that people who ordered the PS4 version of the game will be getting discs. It also provides links to other FAQ pages (oddly enough for the US/North American versions of the games), laying out the contents of the Collector's Editions, which Ubisoft has attempted to reassure customers will be in the packages when they ship through the British postal service.
There has not been any indication of why Ubisoft seems to be taking this particular move at this particular moment. Shortly after the notification went up, Polygon reported that Ubisoft confirmed with them that customers in North America would be receiving discs in their collector's editions. However, the publisher has still had not provided any reason for what prompted the move.
None of the release dates for the games in question have been changed at this point. Watch Dogs: Legion is still on track for an October 29 release date. Assassin's Creed Valhalla will be coming out on November 17. And Far Cry 6 has not shifted (yet) from its February 18 release next year. All three titles are slated to come out on PC, Xbox Series X, PlayStation 5, and Google Stadia in addition to their Xbox One and PS4 releases.
Food For Thought
Historically, Yves Guillemot has been a vocal advocate of an "all-digital" ecosystem, where there are no physical media at all for any games. It's unclear if this is Ubisoft's idea of "test marketing" or if they figure things can't possibly get any worse with the company's reputation given the sex scandals of the last few months.