What is the point of moving libexif-gtk to GTK3 when the only package
using it does not support it?
This sounds like a mistake that should be reverted.
I already have. When I realised gtkam was an issue, I updated libexif-gtk to build both GTK 2 and 3.
Unfortunately, gtkam is dead upstream, so nothing will change there. However, several good alternatives exist.
The Debian QA team is also reluctant to remove gtkam due to its popcon installation numbers.
That said, as libexif-gtk will have GTK 2 support for some time, this bug severity can probably be downgraded.
If smcv does manage to remove GTK 2 during the next development cycle, however, we will need to revisit this bug.