you're right and I think I isolated the problem...

Neither Data::Dumper nor Data::Dump are buggy, it's Perl who stores the current package-name into a slot *$fh{PACKAGE} of the globref in $fh

> perl
package BLA;
$\="\n";
open my $fh,">",'/tmp/tst';
print "globname: ", *$fh{NAME};
print "globpkg: " , *$fh{PACKAGE};
print 'Stashkey $BLA::{$fh} found? ', scalar grep {/\$fh/} keys %BLA::
+;
__END__
globname: $fh
globpkg: BLA
Stashkey $BLA::{$fh} found? 0
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*$fh{PACKAGE} should be empty or undef or hold a magic dummy