but for some reason this results as an infinite loop,

This has nothing to do with multi-level hashes. Something (keys, values or each) in the loop (in ...) must be reseting the %$fruits_xml's iterator.

my %h = qw( a 1 b 2 c 3 d 4 );

for (1..2) {
    my $i = 0;
    while (my ($key) = each %h) {
        print $key;
        keys(%h) if $_ == 2;   # Reset %h's iterator in second test.
        last if ++$i == 10;    # Break out of infinite loop.
    }
    print("\n");
}
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$ perl a.pl
cabd
cccccccccc
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