this is like https://bugs.archlinux.org/task/69135 you basically rsync to a remote server on an rsync module, and get Operation not supported (95) errors. Applying the syscall.c part of https://github.com/WayneD/rsync/commit/9dd62525f3b98d692e031f22c02be8f775966503.patch makes it work fine again for me. Please consider applying the relevant part of above patch (I can do it too, if you want).
(I'll CC toolchain@ as it's worth them being aware of various glibc issues, even if it's an rsync bug.)
The bug has been closed via the following commit(s): https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=aa02f9c1783dd7bc1bb4ceb1bfe776e33b9536c6 commit aa02f9c1783dd7bc1bb4ceb1bfe776e33b9536c6 Author: Mike Gilbert <floppym@gentoo.org> AuthorDate: 2021-04-19 01:00:13 +0000 Commit: Mike Gilbert <floppym@gentoo.org> CommitDate: 2021-04-19 01:01:07 +0000 net-misc/rsync: backport glibc lchmod workaround Closes: https://bugs.gentoo.org/777483 Closes: https://github.com/gentoo/gentoo/pull/20410 Signed-off-by: Mike Gilbert <floppym@gentoo.org> .../rsync/files/rsync-3.2.3-glibc-lchmod.patch | 58 ++++++++ net-misc/rsync/rsync-3.2.3-r3.ebuild | 152 +++++++++++++++++++++ 2 files changed, 210 insertions(+)