The issue comes from the ICC profile:
1) convert the jxl into png and/or jpg using djxl
2) compare the 2 or 3 files with XnView; They look very similar, but their looks depend on whether the color management (use ICC profile) is activated or not:- if not, all look dark, if yes, all look pale
What is a bit strange for me is that exiftool finds an ICC profile in both the png and the jpg generated from the jxl but not in the jxl itself. With jxlinfo, one gets Color space: 548-byte ICC profile, CMM type: "appl", color space: "RGB ", rendering intent: 0
