We come back with the results of the investigations:
The GDAL native library fail to load because a dependency library (libjpeg.8.dylib) is loaded from your system instead of being loaded from the SNAP internal GDAL distribution bundle. This library has been removed by one of the last system updates and replaced by a newer version (libjpeg.9.dylib).
A JIRA ticket SNAP-3500 has been created to fix this problem and it will be available with the next SNAP update.
Meanwhile, a workaround can be applied to load the dependency library from the SNAP internal GDAL distribution bundle.
To quickly apply this solution on your system please run:
install_name_tool -change "/usr/local/opt/jpeg/lib/libjpeg.8.dylib" "@loader_path/libjpeg.8.dylib" ~/.snap/auxdata/gdal/gdal-3-2-1/lib/libtiff.5.dylib
Regards
Adrian