According to API documentation https://developer.freshdesk.com/api/#filter_tickets
filter tickets supports updated_at field
yet by calling https://mycompany.freshservice.com/api/v2/search/tickets?query=%22updated_at%3A%272019-10-01%27%22
results in 400 BAD request with
{"description":"Validation failed","errors":[{"field":"updated_at","message":"Unexpected/invalid field in request","code":"invalid_field"}]}