But Bergsträßer said it was the best

No, no, no
Bergsträßer wrote: It's better than Flügel.
And he is right.
But he did not know a thing about printed maṣāḥif, had never seen a Moroccan one, nor an Indian, just a few Ottoman prints and one Persian.
On pages 11, 13 of his article in Der Islam he points out a few mistakes in the King Fuʾād edition:
two wrongly placed hamza,
too many big alifs denoting dual,
hamza on the line + alif instead of alif-hamza + long-fatḥa.
He does not mention that on all three points Indian maṣāḥif follow his ideas (or are much closer to his than the 1924 print).
The reason: he had never studied an Indian muṣḥaf.

For us the 1930 world Bergsträßer lived in, is hard to imagine.
Based in Munich   Berlin, Leiden, Paris were far away.
He made it to Istanbul and to Cairo
-- but Baghdaḍ was too far (or too British?).
Karachi, Lahore, Bombay or Delhi were outside his word.
In 2020 one would advise him to fly to London, spent a month in India Office,
but even today I observe that young scholars mistake the 20% of Islamdom between Cairo and Baghdad for the Muslim World.