The list of packages that need to be rebuilt with the new major version of Perl is determined according to the dependency on perl(:MODULE_COMPAT_XXX). In current Fedora, all Perl modules run-require the versioned perl(:MODULE_COMPAT_XXX) provided by perl-libs.

Only packages with compiled code need to have a dependency on the particular version of Perl it was built against. The other packages have to require non-versioned perl-libs which includes all directories used by all Perl modules.

I proposed the change Perl: Replace versioned MODULE_COMPAT_ requires by RPM dependency generator which will solve it. It was approved by FESCo

That requires updating Perl packaging guidelines.
The new proposed guidelines are here: https://pagure.io/packaging-committee/pull-request/1242

How packages will be updated and all the implementation details are explained in the Fedora Change.