I disagree. Here is the full code and FETCH is only called once for each element within the body of the loop:

use strict;
use warnings;

package MyClass;
    use Tie::Array;
    our @ISA = ('Tie::Array');
    our @data;
    # mandatory methods
    sub TIEARRAY { my $class = shift; bless \@data, $class; @data = @_
+; return \@data }
    sub FETCH { print "FETCH: "; my ($self, $index ) = @_; return $dat
+a[$index] }
    sub FETCHSIZE { print "<FETCHSIZE> "; return scalar @data }

package main;    
    
for( @{ tie my @x, "MyClass", "first", "second"; \@x } ) {
    print "In loop = ";
    print "$_\n";
}
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Output:

In loop = FETCH: first
In loop = FETCH: second
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