I think this could be related to https://github.com/Perl/perl5/issues/19378.

As of a couple years ago I stopped checking for equivalence to &PL_sv_yes in my XS files.
Instead I now use SvTRUE_nomg_NN(sv) (and !SvTRUE_nomg_NN(sv) for FALSE).

Nice work choroba.
I think you've earned the right to file the bug report - or the PR, if you prefer ;-)

Cheers,
Rob