Yes it does. I suggest to keep guest-fsfreeze in order to have consistent backups.
Mandatory for SQL databases. I use it to backup a ZFS disk for my SQL Server 2016 (every 2 hours). It locks FS only 2 or 3 seconds.
If it's not the point, you could create your own scripts...
I also do backups with my own scripts (need more history on backup server than on prod.) where I do not lock fs of guest.
Unless database spans across multiple ZFS volumes, snapshots should be atomic and databases as well as journaled fs shoud have no problem.
But I will leave it on, unless it starts to become a real problem (I do 1 minute sync interval). I just investigated where does these guest fs freezes come from.