Hello,
When I try to browse my phone from my laptop (manjaro xfce) using the 'browse device' function of kde connect, it opens either a catfish file search window (or do nothing) instead of a file browser window.
Thank you.

Are you trying to browse your phone from the kde connect system tray icon? I can't browse my phone either from there. But if I open dolphin, in the "Devices" navigation panel, there is an entry for my phone and I can browse it from there.