rsync freezes FreeBSD machine

Hello to you all!

I am doing a backup for some machines (OpenBSD and Linux) to a FreeBSD
machine (13.1-RELEASE-p5) with ZFS using rsync (usually with `-avhz`).
The problem I always encounter is that if I do an rsync to FreeBSD
everything is smooth, but the other way around, after some files
copied, the FreeBSD machine hangs. I tried even using
`--bwlimit=5000`, but it is the same. I can't ssh, nothing. Just hard
restart.

I tried looking in the logs but I didn't get any useful information.

Any hint?