You have HTTP logs tracked, you don't need to report them twice, once in the HTTP log and once on the backend. You're just effectively raising the error to the HTTP server and its logs are where the errors live. You don't alert on single HTTP 4xx errors because nobody does, you only raise on anomalous numbers of HTTP 4xx errors. You do alert on HTTP 5xx errors because as "Internal" http errors those are on you always.
In other words, of course you don't alert on errors which are likely somebody else's problem. You put them in the log stream where that makes sense and can be treated accordingly.
In other words, of course you don't alert on errors which are likely somebody else's problem. You put them in the log stream where that makes sense and can be treated accordingly.