I think that's because Sebastian develops software for the Librem 5 and thus is likely not running a stock PureOS Byzantium.
I managed to get similar results in my holidays in late August(on postmarketOS 25.06 with Millipixels 0.23.0 and a patched kernel [1]).
Please note that I just used the Librem 5 as my "mainline Linux camera" and have not had a SIM in it in a while, and thus can't comment on how well postmarketOS 25.06 would work for daily driving.
The only major thing these kernel changes introduce is RAW10 support, which helps photos with high dynamic range that would have visible banding in the shadows otherwise. There are more changes, but their effects are either subtle or unrelated to still photos. Most of the pictures I post have been taken without these changes, only some of the most recent ones used them.
I managed to get similar results in my holidays in late August(on postmarketOS 25.06 with Millipixels 0.23.0 and a patched kernel [1]).
Please note that I just used the Librem 5 as my "mainline Linux camera" and have not had a SIM in it in a while, and thus can't comment on how well postmarketOS 25.06 would work for daily driving.
[1]: Based on the APKBUILD in postmarketOS (https://gitlab.postmarketos.org/postmarketOS/pmaports/-/blob...) with https://source.puri.sm/Librem5/linux/-/merge_requests/816.pa... added on top.