The exceeding of API calls limit means that you have a lot of active users who generate the amount of API calls which exceeds the limit of your current plan.
Please be informed that if at some point of time your app generates the number of API calls per second more than it is allowed according to your plan, you receive an email with exceeding the API calls limit.
Below you can find API calls limits for the QuickBlox Cloud customer plans:
Basic plan: 80/per second.
Startup plan: 120/per second.
Growth plan: 160/per second.
Enterprise plan: unlimited.
The email regarding API call rate limit has been exceeded is not related to the number of your application users.
Note, that this is not a critical warning, but it means that there are spikes of your app activity and during these peaks, some of your users may get "429 - Too many requests” error response https://docs.quickblox.com/reference/errors
You can handle this error “429 - Too many requests” by your application logic.
An API call is any call made to a server, in this case to our server.
For example, every time your users log in, send a message or add users to a friend list, they are in fact making an API call.
In case you or your development team apply all possible changes to reduce the number of generated API calls and you still receive this message regarding the exceeding API calls limit, then there is only one way to avoid this issue: upgrade your plan.