A few other approaches...

grep

if (grep { $bands[0] eq $_ } qw(red green blue yellow))
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List::MoreUtils

use List::MoreUtils qw(any);
if (any { $bands[0] eq $_ } qw(red green blue yellow))
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Hash, map, exists

my %colors = map { $_ => 1 } qw(red green blue yellow);
if (exists $colors{$bands[0]})
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