Order By Date desc evaluates 01-01-1970 higher then everything else

I have the following simplified query

SELECT 
   id
   to_char(execution_date, 'YYYY-MM-DD') as execution_date
FROM schema.values
ORDER BY execution_date DESC, id DESC

execution_date can be null.

If no value is present in execution_date it will be set to 1970-01-01 as default. My problem is, that the following table values will lead to a result where 1970-01-01 is treated as the newest date.

Table:

Result I would expect

What I get

How can I get the correct order and is it possible to easily return an empty varchar if the date is empty?

>Solution :

https://dbfiddle.uk/?rdbms=postgres_14&fiddle=5d1fc31a3cf2d3121092f2446cce87e5

SELECT 
   id,
   to_char(coalesce( execution_date, '1970-01-01'::date), 'YYYY-MM-DD') as execution_date
FROM values1
ORDER BY execution_date DESC, id DESC;