Same Issue here on 6.11.1 when using Robocopy to mirror a number of files from a windows machine to the share, no macOS devices on the network.
smb-extra.conf:
#async io
aio read size = 1
aio write size = 1
#turn off sendfile due to problems with ZFS
use sendfile = no
#Enable RSS
server multi channel support = yes
interfaces = "[IP of the Server];capability=RSS,speed=10000000000"
[share]
path = /mnt/zpool/share
comment = share
browseable = yes
guest ok = no
writeable = no
read list = @users
write list = @users
valid users = @users
case sensitive = auto
preserve case = yes
short preserve case = yes
vfs objects = catia fruit streams_xattr shadow_copy2
shadow: snapdir = .zfs/snapshot
shadow: format = zfs-auto-snap_%S-%Y-%m-%d-%H%M
shadow: sort = desc
shadow: localtime = no
veto files = /._*/.DS_Store/
[more shares with the same settings]
Removing fruit and the veto files from the share and restarting samba did not change the behavior.
smb-shares.conf is empty.
The Robocopy command for reference:
robocopy.exe /SD:C:\Directory /DD:\\NAS\share\folder /IF *.* /XD [some excluded subfolders] /S /E /DCOPY:DA /COPY:DAT /PURGE /MIR /xjd /R:1 /W:0 /NFL /NDL /NP /NS /NC /MT:32