That's ok for me, but I thought that things work by default.

The real problem is mentioned here: https://wiki.freebsd.org/BjoernZeeb/Ten64

If loaded as module from multi-user we do not get the time set even if manually triggering a sysctl debug.clock_do_io=1. Reason for this is that vfs_moutroot() is responsible to have the clock set and calls CLOCK_GETTIME() indirectly so that log files or other timestamps do not appear to go backwards (if no RTC is found it'll use the vfs root node date?). Look for the inittodr() call.

One note from a ports maintainer perspective: rust currently uses FreeBSD 11 syscalls. Although those are new binaries, they need COMPAT_FREEBSD11, even for powerpc64le (which was introduced in 13.0). There is long-going plan to bump that to 12, but even then we'll still need COMPAT_FREEBSD12.
Another thing: dropping support for running old binaries (as in compiled long ago) is not an issue for me (and probably most users), but then ELFv1 support should probably also be dropped. We switched to ELFv2 in 13.0.