In 1993's "Dimensions In Time" Children In Need special, the Rani is involved in multiple Fourth Wall breaks. While this may not strictly be canon, it does seem like Mrs. Flood's own fourth wall breaks are an allusion to the Dimensions In Time special.

While I don't recall the Classic Doctor Who having Christmas Specials, that type of episode has occurred often in the New Series. A frequent occurrence of the New Series' Christmas Episode is a further breaking or bending of the Laws of the Universe, including Time.

So I think that an Exception exists within the Timey Wimey Ball for the Doctor, specifically when they take on a persona consistent with a Midwinter Festival, for them to have ample leeway with the rules.

So Twelve can defeat a dream inducing alien with the assistance of an imaginary Santa Claus they have just hallucinated. Or Eleven can create a sphere within which the Blinovitch Limitation does not cause a release of energy. Or Fifteen can create a bootstrap paradox without bad things happening.

These exceptions only occur during a Midwinter type Festival on any given planet, so Fifteen must deal with the full force of the Blinovitch Limitation because his action does not take place during a Midwinter Festival.

The Doctor being unable to save the day is actually a fairly common occurrence in New Doctor Who. The Ninth Doctor, Christopher Eccleston, did several episodes where he had to be saved by a human being: "Rose," "Dalek," "The Unquiet Dead". During David Tennant's run we saw "Midnight," where an incapacitated Doctor must be saved by a human being. I feel that Gatwa's Doctor is being unfairly singled out for a regular occurrence in New Doctor Who.