USCIS is no longer accepting escalations after 75 days for delayed applications for employment authorization. The 75-day policy had been in place when regulations required USCIS to adjudicate employment authorization applications within 90 days of filing. That regulation was rescinded in 2017, and USCIS now has no time limit within which it must act. (In fact, adjudication of these applications now take as long as 7 months, although the pace has been picking up).
Going forward, USCIS will only accept service requests for cases outside of USCIS’s posted processing times, which can be found at https://egov.uscis.gov/processing-times/.