See the related ticket https://rt.perl.org/Ticket/Display.html?id=121299 .
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via perlbug: queue: perl5 status: rejected
https://rt.perl.org/Ticket/Display.html?id=76622
[perl #76622] Regex recursion and backreference: 11 !~ /(^)(|1(?2)\1)$/
by Zsban Ambrus via RT