librust-gtk4-layer-shell-dev is declared Multi-Arch: same, but fails to
coinstall.

The file /usr/share/cargo/registry/gtk4-layer-shell-0.6.3/GLib-2.0.gir
is shared by librust-gtk4-layer-shell-dev version 0.6.3-3+b1 as present
in unstable with varying content.

Please ensure that shared files have bit-identical content across
architectures, move architecture-dependent files to
architecture-dependent paths or remove the Multi-Arch: same field.

Kind regards

Helmut Grohne