Rate limiting occurs in a couple of places. If you receive an email saying rate limiting occurred, it will tell you which endpoint it happened on and how many calls were made.
The other time rate limiting can occur is when your organization exceeds the monthly number of calls allowed per your plan. If your organization exceeds your monthly limit, Stream is alerted and a team member will send out an email notifying you of the exception and giving you the ability to upgrade your plan. If no action is taken by you to respond or upgrade your plan, the rate limiter will turn on to get your total number of calls under the limit for your plan.