`read_exif` seems to be deprecated

[harminius]

https://merginmaps.com/docs/layer/exif/#how-to-use-exif-metadata-in-mergin-maps-mobile-app

This works for me:
exif(@project_home + '/' + "photo", 'Exif.Photo.DateTimeOriginal')

[harminius]

Ahh, now I see it is valid that QGIS doesn't know it. The App should understand that anyway.
In that case, it appears to be a bug in the App.
So it could just be a suggestion/question if docs can promote exif function, which is QGIS compatible.