Hello,

it seems that Debian uses

/etc/sddm/Xsession

to be launched by sddm (it is built with -DSESSION_COMMAND="/etc/sddm/
Xsession). The default value of this switch is

/usr/share/sddm/scripts/Xsession

This file is also installed, but it seems to be ignored by sddm in Debian.
Maybe it's better to remove it?
Debian Release: buster/sid
  990 testing         ftp.by.debian.org
  500 unstable        ftp.by.debian.org
--- Package information. ---
Depends                       (Version) | Installed
=======================================-+-================
adduser                                 | 3.118
qml-module-qtquick2                     | 5.11.2-3
x11-common                              | 1:7.7+19
xserver-xorg                            | 1:7.7+19
 OR xserver                             |
debconf                       (>= 0.5)  | 1.5.69
 OR debconf-2.0                         |
libc6                         (>= 2.14) |
libgcc1                      (>= 1:3.0) |
libpam0g                  (>= 0.99.7.1) |
libqt5core5a                (>= 5.10.0) |
libqt5dbus5                 (>= 5.6.0~) |
libqt5gui5              (>= 5.6.0~beta) |
libqt5network5              (>= 5.6.0~) |
libqt5qml5                   (>= 5.0.2) |
libqt5quick5                 (>= 5.0.2) |
libstdc++6                     (>= 5.2) |
libsystemd0                             |
libxcb-xkb1                             |
libxcb1                                 |


Recommends                  (Version) | Installed
=====================================-+-===========
haveged                               | 1.9.1-6
libpam-systemd                        | 239-13
sddm-theme-debian-maui                |
 OR sddm-theme                        |


Suggests                      (Version) | Installed
=======================================-+-===========
libpam-kwallet5                         | 5.14.3-1
qtvirtualkeyboard-plugin                |
-- 
Alexander Kernozhitsky