I tried to apply Sweet - New Flavor - GTK3/4 Themes, but I used this command (by terminal) in ~/themes folder. (not .themes folder, my bad)
gsettings set org.gnome.desktop.interface gtk-theme Sweet
gsettings set org.gnome.desktop.wm.preferences theme Sweet
Since then I can't change the appeareance of my Ubuntu in tweaktool. I don't know how to fix it.
