Contacts list API q parameter

I am attempting to query the contacts list api and including a parameter to only get contacts updated in the last 3 days.   

I understand how to construct the UNIX time stamp (I think.)

My question is when I do the curl command below and update a single contact in our testing instance of Front I get back all contacts no matter the updated_at date.  Am I misunderstanding how the q works and should I only get a list of the ones that have been updated?

curl --request GET \
     --url 'https://api2.frontapp.com/contacts?q=\[update_after\]=1679933002.000' \
     --header 'accept: application/json' \
     --header 'authorization: Bearer <token>'

Result for contact when it has not been updated

"updated_at": 1679932512.707,

Result for contact after I update it

"updated_at": 1679933920.514,

In both cases I am still getting a list of all contacts.