Pynchon signed a letter defending him. Rumors are they are some kind of friends because he doesn't do this for strangers.

[Mark Kohut]

His new editor is the terrif editor who now holds Sonny Mehta's 'chair' ,
so to allude. The woman who discovered and "made' Kate Atkinson and
Ian Rankin, Pynchon lover, among others. ( I was quoted in the NYT about
Kate Atkinson's success, but LOL, that is a lie. Ms Arthur told
the new company President to talk to *me* about her sales, not the
higher-titled executives so I was the President's short speech writer, so
to speak. So I am biased toward her.

 We have chatted about Ian and his love of Pynchon. (He decided to do his
PH D--I think, unless it was just a Master's equivalent-- on Muriel Spark.
He has at least one very GR story).
Reagan is talking about how thrilled she is; Given McEwan and the company
publishing and his age, this novel will be his most huge in decades, I
predict. (Unless it is, doubtfully, real bad)
A major book reviewer for a major newspaper once said he so loved
McEwan....it was almost sinful to review him,--- so to
religiously dramatize; not the reviewer's words.

https://www.oprahdaily.com/entertainment/books/a39841117/ian-mcewan-lessons-cover-reveal/?fbclid=IwAR3JAc8D30K3zeAEEK4V8BS9DNllzSpbl2Vd0FJ9ry3bEMzr1AYeqhiPt6o