Always config directory is default.
pomodoro history --directory ~/.config/pomodoro
I've tried it with question marks and slash in the end.
To be honest the default directory on the linux should be "XDG_CONFIG_HOME" according to the specification:
https://wiki.archlinux.org/title/XDG_Base_Directory
I installed via arch aur aur/openpomodoro 0.3.0-1 but pomodoro -v prints:
pomodoro version dev