For as long as I can remember (and the difference may be that the 4XL launched with multiframe superresolution support), it seems like the DNGs are created using the old tiled align-and-merge pipeline and not the new MFSR one.
Some previous articles on DPReview claimed that Google was remosaicing the results of MFSR for compatibility - but if they were actually doing that, we wouldn’t be getting a crippled crop.
Sadly, DNG output from the Pixel 4 is substandard compared to the JPEGs thanks to this crippling.
It’s one case where Apple did a MUCH better job. Rather than say “Well some software can’t handle demosaiced DNGs, let’s cripple our implementation for compatibility” they said “This feature is important enough that any software which lacks support just needs to be updated.”
Honestly, I’m aware of almost nothing that doesn’t actually support demosaiced “linear DNG” files. (Which, as I think I’ve mentioned elsewhere, aren’t always actually linear! But nonlinear DNGs are quite rare)