LMDE's apt reports wrong version of packages

[GMTSE]

Hi,

I needed to access Emacs 29.4, so I've activated the "backports" repos for Bookworm in LMDE, following this tutorial:
https://linuxcapable.com/how-to-install-backports-experimental-repository-on-debian/

Since I was used of using standard Mint & Ubuntu, and I didn't notice the final remark, saying that you need to use "-t bookworm-backports" flags to apt to specifically install/configure packages from backports, I started using "apt" the "usual way" (no flags) after configuring the additional repos.

I was very surprised to observe that apt is totally wrong about what it does!!!

# apt install emacs --update
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
emacs is already the newest version (1:29.4+1-4~bpo12+1).
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

$ emacs --version
emacsclient 28.2

Even when purging and reinstalling Emacs, apt reports installing version 29.4, whereas it is still version 28.2 that gets installed!!!!

[georg41980]

APT behavior in short:

Without -t bookworm-backports:

Installs packages from the main repositories (stable versions).

Example: sudo apt install emacs → Installs version 28.2.

With -t bookworm-backports:

Installs packages from the backports repositories (newer versions).

Example: sudo apt install -t bookworm-backports emacs → Installs version 29.4.

Why?

Main repositories: Stability (tested versions).

Backports: Newer versions, but optional and explicitly requested.