pki is from NSS, the Netscape Security Suite. Mozilla is in charge of it and has been since they took over from Netscape.
Note that Firefox etc leave those files (actually older ones as our old browser currently ships with an older NSS) in their profile.
Edit: Looking at the source, nss\lib\sysinit\nsssysinit.c, I see this comment.
/**
* Return the path to user's NSS database.
* We search in the following dirs in order:
* (1) $HOME/.pki/nssdb;
* (2) $XDG_DATA_HOME/pki/nssdb if XDG_DATA_HOME is set;
* (3) $HOME/.local/share/pki/nssdb (default XDG_DATA_HOME value).
* If (1) does not exist, then the returned dir will be set to either
* (2) or (3), depending if XDG_DATA_HOME is set.
*/
So try deleting (or moving out of the way) c:\home\.pki with Dooble closed and see where it is created with XDG_DATA_HOME set.