The foundling falls from a cliff top in The Timeless Children (2020).
Tucked away on the DVDs and Blu-rays of The Complete Fifth Series are two Doctor Who mini-episodes called Meanwhile in the TARDIS. In the second of those episodes we finally learn the answer to one of the longstanding Doctor Who questions: the reason why the Doctor travels with others.
It’s because, after a while, everything in the universe becomes just ‘stuff’. “You make all of space and time your backyard and what do you have? A backyard.” But when he’s with someone seeing it for the first time, he sees it as they see it. He sees with fresh eyes; he sees it properly.