apt install on bookworm permission errors

[sleepy-nols]

When installing the latest release from the .deb file some permission errors appear. I will see if I can fix this later.

apt install ./abrechnung_1.0.0+bookworm1_amd64.deb

...
Setting up abrechnung (1.0.0+bookworm1) ...
adduser: Warning: The home dir /var/lib/abrechnung you specified already exists.
Adding system user `abrechnung' (UID 102) ...
Adding new group `abrechnung' (GID 109) ...
Adding new user `abrechnung' (UID 102) with group `abrechnung' ...
adduser: The home directory `/var/lib/abrechnung' already exists.  Not touching this directory.
adduser: Warning: The home directory `/var/lib/abrechnung' does not belong to the user you are currently creating.
Processing triggers for libc-bin (2.36-9+deb12u9) ...
N: Download is performed unsandboxed as root as file '/root/abrechnung_1.0.0+bookworm1_amd64.deb' couldn't be accessed by user '_apt'. - pkgAcquire::Run (13: Permission denied)

[sleepy-nols]

abrechnung.dirs contains var/lib/abrechnung. I think this is in conflict with abrechnung.postinst which creates this dir at a later point with adduser. I guess the dir should also be chowned later on to the right user instead of root.
I am currently unable to build the debian package myself so iwould appreciate any replication.