Wayland changed the way icons are displayed in desktop manager. It can't access pixmap that is set by application using SetIcon() (in wxPython).

If it can't find suitable icon for application, then default blank document icon is displayed. For example, like on following screenshot for Beremiz:

To fix that you have to create file 'Beremiz.py.desktop' with following (fix paths matching your case) content and put it in ~/.local/share/applications

#!python
[Desktop Entry]
Type=Application
Exec=YOUR_PATH/Beremiz.py
Icon=YOUR_PATH/images/brz.ico
Hidden=false
X-GNOME-Autostart-enabled=false
Name=Beremiz