I have installed webmin_1.670_all.deb, but I receive same error like described in https://sourceforge.net/p/webadmin/bugs/4342/
Error - Perl execution failed
Can't use string ("webmin::show_twofactor_form_totp") as a subroutine ref while "strict refs" in use at /usr/share/webmin/acl/twofactor_form.cgi line 58.
1.672 seems to work