Remember that File::Spec is OO (only class methods, but OO nonetheless).

You need either:

use File::Spec;
next if $file eq File::Spec::->curdir() or $file eq File::Spec::->updi
+r();
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or to use the non-OO File::Spec::Functions:

use File::Spec::Functions qw/curdir updir/;
next if $file eq curdir() or $file eq updir();
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