Data visibility for returning statement

The following documentation comment has been logged on the website:

Page: https://www.postgresql.org/docs/17/dml-returning.html
Description:

Today I found a pretty special use-case for the "RETURNING" functionality,
which I cannot find documentation for?
If you have a statement as follows:
UPDATE persons SET name = 'Bob' WHERE id = 4
RETURNING (SELECT name FROM persons WHERE id = 4)
The returning data will be whatever the value was before the row was
modified. This differs from if I were to "RETURNING name". I found this to
be interesting and could possibly warrant some kind of explanation in the
documentation?
Best regards
Robin