Reported to the developers mailing list by Anke Biekoetter:

Dear EvtGen developers,

I just came across a small typo in the EvtGen default DECAY.DEC files:

The BR for B+ -> eta' l+ nu is listed as

0.000230 eta' mu- anti-nu_mu PHOTOS ISGW2;

However, it should be 2.3*10^-5 instead of 2.3*10^-4 [1]. So there is
one zero missing there, I think.

I realized that I had quite a large eta' peak in semileptonic B->Xu l nu
decays and I think this is just a typo in the default decay card.

I just thought that you might want to update this in future versions.

Best,

Anke

[1] https://pdg.lbl.gov/2020/tables/rpp2020-tab-mesons-bottom.pdf (page 8)