Mahler Symphony 5: Notes say Db but recording says D

Question

I've been practising Mahler's 5th Symphony for quite a while now on the piano (the transcription/arrangement by Otto Singer II) and I recently realized that I was playing a D instead of a D-flat, which is what the notes actually suggest:

This is a passage from the third movement (the Scherzo). When playing it again with a D-flat it sounded so off compared to what I had heard countless times listening to this recording that I had to go back and check:

Bernstein - Mahler 5

No matter how many times I replay that part I keep hearing a regular D. The same goes for this one conducted by Barenboim. I did read this question about why some recordings seem to be in a different key, but that is not the case with this question. It's literally just this one note during this passage.

Am I hearing this correctly? - I don't have perfect pitch but this seems pretty clear to me - Am I wrong? Are both my ears and my piano so far out of tune? I have a strong feeling that I'm missing something pretty simple here, but what?

I also thought that it might just be a transcription error so I looked into the orchestra score but that one also says D-flat:

Answer 1

The first edition of the score (Peters, 1904) has D naturals.

The Peters "revised edition" (also dated 1904, but issued in 1905) has D flats.

The Peters Urtext edition (1964) has gone back to D naturals.

"Revised" doesn't always mean "better"!

All three editions are on IMSLP.

Answer 2

The individual parts on IMSLP are from a different edition, and have accidentals turning those notes into D♮'s:

(From the Flute I part, p. 9.)

Which version is "right" I can't say, but at least you know that you're not going crazy.