/(?(?{pos() % 2 == 0})(b[xyz]))/g

I think you want to explicitly back-track in the no condition...

/(?(?{pos() % 2 == 0})(b[xyz])(*FAIL))/g

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package Cow { use Moo; has name => (is => 'lazy', default => sub { 'Mooington' }) } say Cow->new->name

In reply to Re^2: A regex that only matches at offset that are multiples of a given N? by tobyink
in thread A regex that only matches at offset that are multiples of a given N? by BrowserUk

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