No tray icon with Flatpak

I am using the flatpak app under Plasma with Wayland, no tray icon to be seen, even when the setting is checked.

Delta Chat version

Delta Chat Desktop 1.56.0 (git: flathub)
Delta Chat Core v1.157.3
SQLite 3.45.3
electron 34.0.1
node 20.18.1

System

Operating System: openSUSE Tumbleweed 20250427
KDE Plasma Version: 6.3.4
KDE Frameworks Version: 6.13.0
Qt Version: 6.9.0
Kernel Version: 6.14.4-1-default (64-bit)
Graphics Platform: Wayland
Memory: 7.3 GiB of RAM
Graphics Processor: llvmpipe