The entry for sddm in /usr/ports/UIDs has $HOME=/usr/local/etc/sddm/home.
I believe this is incorrect as sddm uses $HOME to store state instead of configuration; and hier(7) suggests that /usr/local/etc should only have configuration files instead of transient files. sddm modifies the contents of $HOME whenever someone logs in/out.
I would suggest its $HOME be relocated to /var/sddm.
*** This bug has been marked as a duplicate of bug 244756 ***