I can remember talk on the digikam mailing list about interoperability of the rating tags with DT. And DT uses it’s own namespace in xmp, right? There’s no reason digikam should overwrite that. I just tested with my very outdated appimage of digikam (a beta of 6.0.0, as I don’t have time to recompile digikam right now):
- Open a raw image in digikam, set a rating.
- Open that image in DT: Rating is visible. Change some processing parameters and close DT.
- Back in digikam change rating and add a tag.
- Go back to DT: Processing is still applied.