At 21:09:00 UTC 25 June, we released an update to our API layer that inadvertently started to count WebSocket subscriptions to certain tables against the request rate limit that had otherwise been exempt. This update may have impacted customers who heavily utilise the WebSocket API. Once the issue was identified at 00:19 UTC 26 June, we immediately rolled back the update to bring systems back to normal.
We apologise for any inconvenience this may have caused. To read more about which subscriptions are exempt from the request rate limiter, see our previous blog post [https://blog.bitmex.com/update-to-our-realtime-apis-image-delivery/] for details.