If there's an issue with i3/regolith key cobination interfering with keyboard layout shortcut for switching between layouts you can remove the shortcut by 2 ways.
dconf write /org/gnome/desktop/input-sources/xkb-options "['grp:caps_toggle']"
Installing gnome-tweaks
sudo apt install gnome-tweaks
and go to “Keyboard & Mouse” then Additional Layout Options then “Switching to another layout” and uncheck the box (or select some other key combo) from the key combination.
Check the configuration before and after. This is an example when no key combo has been set. Before:
~$ dconf read /org/gnome/desktop/input-sources/xkb-options ['grp:ctrl_alt_toggle']
After:
~$ dconf read /org/gnome/desktop/input-sources/xkb-options @as []
Alternatively use
setxkbmap -query
under options it will show the set keyboard combo or it will not show anything if there isn't a combination set up.