It is also an issue for me. And it has been for a long time.
Current system info:
Steam Beta Branch: Steam Beta Update
Steam Version: 1764106918
DE: KDE Plasma 6.5.3
Distro: Debian Sid
Kernel: 6.16.12+deb14+1-amd64
Session type: X11
Nothing extracted yet.
The updater UI window is not displayed when Steam is launched.
For the rest, the application works correctly.
Steam (flatpak) 1.0.0.81
GNOME 47
Fedora Workstation 41
Linux 6.13.10