BUG #16238: Function " to_char(timestamp, text) " doesn't work properly

The following bug has been logged on the website:

Bug reference: 16238
Logged by: Nick Memos
Email address: memnik(at)hotmail(dot)com
PostgreSQL version: 10.7
Operating system: Windows 10
Description:

Hello,
I have created a table with a json column. Where in this json i have some
details for each day of the week. It is something like this '{"Monday":
13,"Tuesday": 13,"Wednesday": 13, "Thursday ": 12, "Friday": 13,"Saturday":
13,"Sunday": 13}'::json.
So, when i try to get the information for each day by this way: '{"Monday":
13,"Tuesday": 13,"Wednesday": 13, "Thursday ": 12, "Friday": 13,"Saturday":
13,"Sunday": 13}'::json->>to_char(current_timestamp,'Day') , i don't get the
results for all days. As i noticed the problem is that the function "
to_char(timestamp, text) " doesn't work properly. For example this query "
select to_char('2020-01-29'::date,'Day') " give me this result "Wednesday",
but this query " select to_char('2020-01-31'::date,'Day') " give me this
result "Friday ".
So, i guess it is not right to have days with many spaces as a result and
some days without any space.
Now i will user trim() function but it is better to fix that if it is
possible.
Thanks!