to redefine the AJAX action, you can try that
add_action(AE_Base::AJAX_PREFIX . "ae-profile-sync", function () {
$profile_action = $GLOBALS["et_freelance"]->profile_action;
// remove base action
remove_action(
AE_Base::AJAX_PREFIX . "ae-profile-sync"
,
[
$profile_action,
"sync_post",
]
, 10
);
// add new AJAX action
add_action(
AE_Base::AJAX_PREFIX . "ae-profile-sync"
, function () {
// new code here
}
);
}, 1); // priority 1 to launch this before the method sync_post