gcc-12/mips64el FTBFS during sbuild chown

https://buildd.debian.org/status/logs.php?pkg=gcc-12&arch=mips64el

...
Finished
--------

I: Built successfully
chmod: cannot access '/<<PKGBUILDDIR>>/build/mips64el-linux-gnuabi64/libstdc++-v3/testsuite/normal3/filesystem-test.FSLTZS-last_write_time': Value too large for defined data type
chmod: cannot access '/<<PKGBUILDDIR>>/build/mips64el-linux-gnuabi64/libstdc++-v3/testsuite/normal2/filesystem-test.5zDnmX-last_write_time': Value too large for defined data type
E: Can't chmod /<<BUILDDIR>> to g+w: 
E: chmod g+w /<<BUILDDIR>> failed.
du: cannot access '/<<PKGBUILDDIR>>/build/mips64el-linux-gnuabi64/libstdc++-v3/testsuite/normal3/filesystem-test.FSLTZS-last_write_time': Value too large for defined data type
du: cannot access '/<<PKGBUILDDIR>>/build/mips64el-linux-gnuabi64/libstdc++-v3/testsuite/normal2/filesystem-test.5zDnmX-last_write_time': Value too large for defined data type
E: read_command failed to execute du
E: Cannot determine space needed for /<<PKGBUILDDIR>> (du failed)
...


This is apparently mips64el-only (no problem on mipsel),
and it is not obvious how to reproduce it on the porterbox.

The timing when the issue started matches when coreutils 9.1-1
started being in the chroot (but the problem might be elsewhere).

Any clues what might be going wrong?

Thanks
Adrian