Issue with samba transfers of some files only (mac os Big Sur client)

Hi,
I’m running linux Manjaro latest stable 20.2 Nibia with lts 5.4.77-1.
Manjaro runs a samba server (v. 4.13.2-1).
Manjaro runs qemu for a mac os virtual machine (Big Sur 11.1 beta, but this was happening since Big Sur beta 7).
Shares on Manjaro are accessible from the virtual machine with smb.
Samba configuration file:

[global]
access based share enum = yes
bind interfaces only = yes
interfaces = lo br1
local master = yes

[2TB]
path = /media/2TB
browsable = yes
Force User = nobody
valid users = user
write list = user
vfs objects =

[6TB]
path = /media/6TB
browsable = yes
Force User = nobody
valid users = user
write list = user
vfs objects =

[VM]
path = /media/VM
browsable = yes
Force User = nobody
valid users = user
write list = user
vfs objects =

For some reason I can’t understand Big Sur fails to transfer some files: this means that some files cannot be transferred (always), some other can be transferred without issues.

This does not happen with another mac os Catalina virtual machine I have: files which cannot be transferred in Big Sur can be transferred without issues in Catalina.

I tried to zeroes the free space of the disks in which the shares are, without luck.
I captured 2 sessions of wireshark in Big Sur, one for a successfully transferred file (successful.pcapng) and one for an unsuccessful transfer (unsuccessful.pcapng).

I tried to read the captures but I don’t understand too much, and I cannot understand where the issue is.

Captured packets are here if someone wants to have a look at them:
https://workupload.com/file/ajjpuxKNUUk

NFS protocol has no issues with this Big Sur, all the files can be transferred, so the issue is with smb or with the new big sur os.

Thanks for any help