Man pages matching name regexp::grammars in section 3pm:

Regexp::Grammars.3pm.en	debian 10 / libregexp-grammars-perl
Regexp::Grammars.3pm.en	debian 11 / libregexp-grammars-perl
Regexp::Grammars.3pm.en	debian 12 / libregexp-grammars-perl