Why a page's INP score can drop after an extra fast click

A developer found that a page's Interaction to Next Paint (INP) score can fall after one more click even though the slow interaction remains unchanged. The score depends on how the browser groups related Event Timing entries and which interactions are kept, so it can select a different interaction as the visit grows. INP ignores one of the longest interactions for every complete group of 50, which means that at the fiftieth interaction the reported value can shift to a lower latency. The article provides worked examples and a selection code snippet, and it notes that browsers only expose events above a default duration threshold. The author recommends using the web-vitals library for production collection and tracking the selected interaction's latency and ID alongside the total interaction count.