Created attachment 173089 [details]
original file from Pixel 5

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***

SUMMARY


STEPS TO REPRODUCE
1. Copy an original Pixel image (see attached) to a folder managed by Digikam
2. > digikam &> log.file
3. Check Exiftool to delegate metadata write setting
4. Check "Advanced" metadata mapping setting to default value
5. Type a title, for exemple <a text>
6. exiftool -xmp:title <file>   if "<a text>" retry step 5 with another text until exiftool does not find anymore an xmp-title
(that could take 3 or 4 times to retry)
7. exit digikam and check log.txt, seach for
digikam.metaengine: Exiv2 ( 3 ) :  Erreur XMP Toolkit 102: Unknown namespace prefix for qualified name
digikam.metaengine: Exiv2 ( 3 ) :  Failed to encode XMP metadata.

ADDITIONAL INFORMATION
Debug mode shows an error with Exiv2 (see attached log).
This problem happens also with a Pixel 5 and a Pixel 8.
It does not happen with my Ricoh GR II neither with photos taken with the same Pixel 5 last year ! (I presume the Pixel 5 has been updated to a new version of Android since last year).