What the Health tab shows
Requests and Failed requests show the totals for the last 24 hours. Requests by hour shows when the connection sent requests and which ones failed. Endpoints lists the endpoints the connection called, busiest first, with the number of failures for each. When requests fail, Failed requests by type sorts them into blocked requests, client errors (4xx), rate-limit responses (429), and server errors (5xx). Error codes lists thecode values from error responses. See Status codes for what each code means. Rate limits shows which limits the connection reached. See Request limits for how to handle each one.
The Health tab counts every failed request and a sample of successful requests. Numbers that include successful requests, such as Requests and the share of requests that failed, are estimates and start with ~. When a connection has less traffic, the tab may not have enough data to show these estimates. Failed requests still show.