So, at the end of all i followed a bit of all the advises i found online.
First, I changed the value of my fields to make sure in database is like YYYYMMMDD.
The problem i had was, that the field was filled up through API and ACF could not format the date at the good format in database.
I have to changed the format of the date that i send through the API.
Normal people using the backend to fill up the field date would never have this problem.
Second, i add a line in my code
'date_disponible_clause' => array(
'key' => 'date_available_from',
'value' => $date_from_format_search,
'compare' => '<=',
'type' => 'DATE' // This line
)
Now it’s working very well.
Thanks everybody.