This is probably something to submit upstream, but I'm unsure.
Following a recent reboot, my Wayfire compositor was unable to load the
panel or set a background. I couldn't coax much debugging from them, but
traced it down to a "bwrap" subprocess. I then noticed various apps were
failing, including reportbug. I was finally able (using strace) to find
a failed seccomp call in libglycin's decoders. I rebuilt my kernel with
CONFIG_SECCOMP enabled, and everything worked.
CONFIG_SECCOMP is enabled in the default Debian kernel, but I don't
think building without it is that rare.
In my ideal world, gdk would fall back on some other decoding mechanism
in the absence of kernel seccomp support. I anticipate that this might
be a non-starter either for security or implementation cost reasons. In
that case, it would at least be nice to get obvious and clear failure
diagnostics. This latter choice is most likely done in libglycin itself.
Feel free to reassign this as you see fit.