vectorization is not helping with plural to singular matching

The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/10/textsearch-intro.html
Description:

SELECT to_tsvector('fat cats ate fat rats') @@ to_tsquery('fat & rat'); 

This is giving false, even I tried for various other examples for plural to
singular matching but it fails. 

e.g. select to_tsvector('buildings') @@ plainto_tsquery('building')

This simple match is also coming as false, means vectorization is not
helping with plural to singular matching.

version used: 

PostgreSQL 13.4 on aarch64-unknown-linux-gnu, compiled by gcc (GCC) 7.3.1
20180712 (Red Hat 7.3.1-6), 64-bit