Between May 7, 2021 and June 8, 2021 a misconfiguration in Litmus' Email Analytics caching caused Gmail opens to record lower numbers than expected. The net result is that Gmail opens in Litmus Email Analytics for that period will be 60-70% lower than typical.
This configuration issue has been fixed and from June 8, 2021 forward Email Analytics is back to recording Gmail opens as expected.
We monitor our systems by performing live email and web page tests constantly. Additionally, we measure the response time of the Litmus application and our Email Analytics platform from different locations.