Search Filter CPT, Custom Loop

I have a custom loop to display projects in a grid on my WordPress site. I’m creating filters for these projects and am getting stuck on the input search. I am getting a 400 error on my admin-ajax.php and not sure how to get this working. Can someone give me any tips? Here is my code:

PHP code for loop in functions.php

JS code also in functions.php

I localized the script earlier for another ajax request, so this is where the url is coming from: