[Errors] Update error-502-504.mdx

SPM-2107

Author: ngayerie

src/content/docs/support/troubleshooting/http-status-codes/cloudflare-5xx-errors/error-502-504.mdx

@@ -49,4 +49,13 @@ If you need further assistance from our Support team, provide the following deta
 
 - The time and timezone when the issue occurred.
 - The URL that resulted in the HTTP `502` or `504` response (for example, `https://www.example.com/images/icons/image1.png`).
-- The output from browsing to `<YOUR_DOMAIN>/cdn-cgi/trace`.
+- The output from browsing to `<YOUR_DOMAIN>/cdn-cgi/trace`.
+
+### Known Cloudflare issues leading to HTTP Error 502 or 504
+
+- Using [Gateway](/cloudflare-one/policies/gateway/) can lead to an HTTP Error 502 at the Edge if the origin only partially supports HTTP/2.
+See [the article under Gateway FAQ](/cloudflare-one/faq/troubleshooting/#i-see-error-504-when-browsing-to-a-website) for more details and resolution.
+
+- You may see an influx of HTTP Error 504 with the `RequestSource` of `earlyHintsCache` in Cloudflare Logs when Early Hints is enabled, which is expected and benign.
+See [the Early Hints article](/cache/advanced-configuration/early-hints/#emit-early-hints) for more details and resolution.
+