[Samba] Updating samba with bookworm-backports

[spindles seven]

I have successfully updated several machines to Samba Version 4.18.4 using Debian's bookworm-backports repository, but one machine will not update.   It was happy to update to version 4.17.10 but when I try to upgrade to 4.18.4 I get:

roy at franks:~$ sudo apt upgrade
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
Calculating upgrade... Done
The following packages have been kept back:
  libtalloc2 libtdb1 libtevent0 python3-talloc python3-tdb
0 upgraded, 0 newly installed, 0 to remove and 5 not upgraded.

So I try:
roy at franks:~$ sudo apt dist-upgrade
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
Calculating upgrade... Done
The following packages were automatically installed and are no longer required:
  libcups2 libyaml-0-2 python3-anyio python3-click python3-colorama
  python3-dnspython python3-gpg python3-h11 python3-h2 python3-hpack
  python3-httpcore python3-httpx python3-hyperframe python3-ldb
  python3-markdown python3-markdown-it python3-mdurl python3-pygments
  python3-requests-toolbelt python3-rfc3986 python3-rich python3-sniffio
  python3-yaml samba-ad-provision tdb-tools
Use 'sudo apt autoremove' to remove them.
The following packages will be REMOVED:
  libnss-winbind libpam-winbind python3-samba python3-talloc python3-tdb samba
  samba-common-bin winbind
The following packages will be upgraded:
  libtalloc2 libtdb1 libtevent0
3 upgraded, 0 newly installed, 8 to remove and 0 not upgraded.
Need to get 123 kB of archives.
After this operation, 33.2 MB disk space will be freed.
Do you want to continue? [Y/n]n


That didn't sound god, so I try:

roy at franks:~$ sudo apt -t bookworm-backports install samba winbind
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 python3-samba : Depends: python3-tdb but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

Any advice please?

Also I note only amd64 architecture is available in bookworm-backports.   Is there any plan to add other architectures - specifically arm64 etc?

Thanks,

Roy