UI only opens after the "launcher" program closes

[pitbuster]

Describe the bug
When NeovimGTK is launched from other desktop programs, it only opens the UI after the "launcher" program closes. It has happened when launching it from krunner, dolphin (when openning a text file from the file explorer) and joplin (in the open in external editor option). When launching from a terminal, it works fine.

Technical information (please complete the following information):

• OS: Archlinux with KDE Plasma (Wayland), I haven't tried to reproduce in the X11 session.
• Neovim version: 0.9.1
• Neovim-Gtk build version: cf3a165 (through https://aur.archlinux.org/packages/neovim-gtk-git )

[towo]

Can reproduce (with textern) and using --no-fork.