I expect if you run your test with QEMU v7.2.0-873-g65cc5ccf06-dirty
on any big-endian *host* (like a s390x), the test fails.
I don't have powerpc mac hardware, which seems the easiest way to get such a
test system.
(Well, ok, the EASY way would be to feed qemu-system-s390x a couple gigs of ram
and then build and run qemu within qemu. While I do have a native toolchain for
s390x, qemu's grown an insane dependency stack these days that would be a pain
to bootstrap under a musl beyond-linux-from-scratch environment...)