Black level is changed, when using adobe dng converter to convert .3FR file to dng

I was trying to convert some .3FR files from hasselbald x1d. The original black level of 3FR file is 256, but the black level of dng is changed to 1028. Why is 1028? and is it correct?

please take this photo as an example:

https://www.dpreview.com/sample-galleries/4234210046/hasselblad-x1d-sample-gallery/3168873830

adobe dng converter version I used is 13.4.0.872