This has nothing to do with with XS or not.  It's solely a matter of whether there's a prototype declared for the function.  The exact same problem exists for pure-Perl modules:

#!/usr/bin/perl

package ABC;

sub new_time_var () {
               # ^^prototype

    print "ABC::new_time_var() called.\n";
}

package PQR;
    
sub new_time_var {

    ABC::new_time_var();    # prototype-compatible call --> works
    
    ABC::new_time_var(@_);  # incompatible --> "Too many arguments for
+ ABC::new_time_var ..."
}

new_time_var();
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