More details from TVZone UK https://www.tvzoneuk.com/post/doctor-who-trailer-images-and-cast-revealed-for-anniversary-specials
'Russell T Davies, showrunner says: “We wanted to give fans, friends and families a lovely little Christmas present - with a promise that 2023 will be a riot of Doctor Who goodness!'
ETA: BBC press release that TVZone was cribbing from https://www.bbc.co.uk/mediacentre/2022/doctor-who-sneak-peek-60th-anniversary-year