Your system information

• Steam client version (build number or date):

# LANG=C apt-cache policy steam-launcher
steam-launcher:
  Installed: 1:1.0.0.75
  Candidate: 1:1.0.0.75
  Version table:
 *** 1:1.0.0.75 500
        500 https://repo.steampowered.com/steam stable/steam amd64 Packages
        500 https://repo.steampowered.com/steam stable/steam i386 Packages
        100 /var/lib/dpkg/status

• Distribution (e.g. Ubuntu):

# cat /etc/*lease
PRETTY_NAME="Debian GNU/Linux 11 (bullseye)"
NAME="Debian GNU/Linux"
VERSION_ID="11"
VERSION="11 (bullseye)"
VERSION_CODENAME=bullseye
ID=debian
HOME_URL="https://www.debian.org/"
SUPPORT_URL="https://www.debian.org/support"
BUG_REPORT_URL="https://bugs.debian.org/"

• Opted into Steam client beta?: [Yes/No] Don't know
• Have you checked for system updates?: [Yes/No] sure

Please describe your issue in as much detail as possible:

After the start the client moves its own window from the top left to the bottom right. Even if I try to reposition the window it keeps moving. See here:
https://youtu.be/vWFILxyjeyI

Steps for reproducing this issue:

1. Open xterm.
2. Type in steam
3. Start staring flabbergasted.