I must say that I don’t usually use raw captures, but I was quite surprised by this statement about the size of raw files generated by Picamera2.
I seem to remember that, with older versions of the library, the size of the full resolution dng files was 17.6 MB. I still have some dng files generated by older versions of the library and indeed the size is 17.6 MB.
I just did a raw-dng capture test at full resolution with the HQ camera and I must admit that you are absolutely right. The latest version of the library generates files of 23.5 MB.
The question is, what is the cause of this significant increase in the size of these files?