$ perl -E'say "\x80" =~ /^\x80\z/ ?"match":"no match"'
match

##</code><code>##

$ perl -E'
    use encoding "UTF-8";
    say "\xC2\x80" =~ /^\N{U+0080}\z/ ?"match":"no match"
'
match

##</code><code>##

$ perl -E'
    use encoding "UTF-8";
    $x = "\xC2\x80";
    say $x =~ /^\Q$x\E\z/ ?"match":"no match"
'
match