It was a bit of a "search your feelings you know it to be true" type moment. Taken alone the Master's not really a trustworthy source, but combined with what the Remnant told her in The Ghost Monument, the glimpses of her memories in Spyfall and Can You Hear Me? and the sequences in the Matrix the The Timeless Children that show the Doctor struggling with then starting to accept the revelations, I don't think it's ambiguous.
As far as the Morbius Doctors go, to me, showing their faces interspersed with those of her other past selves was a clear indication they're past incarnations, but if others feel differently, it's probably best to leave them as ambigious let people come to their own conclusions.
But maybe of inventing a third heading, we could retitle the second one so that it can accurately encompass everything?