I just tested ripcord and it didn't seem to work very well on Gnome. Didn't do dpi scaling so it looked tiny on my main monitor and the notifications showed up pretty broken.
Gnome should probably have the correct DPI values, since it's a complete DE, but I'm guessing something has gone wrong with the way the Qt version that Ripcord uses is reading the DPI values.
Try something like:
QT_SCALE_FACTOR=2 QT_AUTO_SCREEN_SCALE_FACTOR=0 ./Ripcord.AppImage