BUG #19643: Output of jsonb_populate_recordset not consistent with documentation description

The following bug has been logged on the website:

Bug reference: 19643
Logged by: Balaji Venkatesan
Email address: yishundinesh(at)gmail(dot)com
PostgreSQL version: 18.6
Operating system: Ubuntu
Description:

As per the documentation jsonb_populate_record "Expands the object in
from_json to a row whose columns match the record type defined by base".
The example given the documentation is working fine, but if I replace
null::myrow with Row(('a'::text,'b'::text), the output discards
from_json(second argument completely)
First argument's value is being used instead of using it as a key

Eg:
select * from
jsonb_populate_recordset(ROW('a'::text,'b'::text),'[{"a":"test","b":"55"}]')
as (a text, b text)

Output::
a,b

Expected output:

test,55