We have identified an issue affecting the accuracy of INP data collected between Thursday, 5 February and Monday, 9 February.
During this period, INP metrics were incorrectly reported for Safari on iPhone when the navigation type was back-forward cache (BFCache). This behaviour is related to a known issue in WebKit, which causes inflated INP values in this specific scenario. More details are available in the related Safari bug report: https://bugs.webkit.org/show_bug.cgi?id=305251
The issue has been identified and mitigated on our side. Only the INP metric is impacted; other performance metrics remain unaffected.
We apologise for any confusion this may have caused and recommend caution when analysing INP data for Safari iPhone traffic over this time window.
If you have any questions, our team remains available.