use strict;
use warnings;
use feature qw/ say /;
use Scalar::Util qw/ blessed/;

open my $fh, ">", undef;

say blessed( *$fh{ IO });                           # IO::File
say *$fh{ IO }-> can( "print" ) ? "yes" : "no";     # no
autoflush $fh 1;
say *$fh{ IO }-> can( "print" ) ? "yes" : "no";     # yes
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And:

use strict;
use warnings;

use Log::Log4perl qw / :easy /;
use Log::Dispatch::Handle;

open my $fh, ">", undef;
#autoflush $fh 1;

my $app = Log::Log4perl::Appender-> new( 
    "Log::Dispatch::Handle", 
    handle => *$fh{ IO });

__END__

The IO::File class is missing the 'print' method
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And uncommenting the comment makes the program run OK and error message gone.