see build https://koji.fedoraproject.org/koji/taskinfo?taskID=36304162
These are the relevant lines in the build log:
BUILDSTDERR: In file included from ../../mono/utils/mono-machine.h:21,
BUILDSTDERR: from ../../mono/utils/mono-context.h:16,
BUILDSTDERR: from mono-context.c:459:
BUILDSTDERR: mono-context.c: In function 'mono_sigctx_to_monoctx':
BUILDSTDERR: mono-context.c:474:17: error: dereferencing pointer to incomplete type 'struct fpsimd_context'
BUILDSTDERR: 474 | g_assert (fpctx->head.magic == FPSIMD_MAGIC);
BUILDSTDERR: | ^~
Seems it builds now in Rawhide without changes, according to Koschei.
I will close the bug on Monday, if the build succeeds.
It seems something outside of Mono was broken in Rawhide, it is working again.