There is an org-wide, 24-hour rolling limit for REST API requests.
The REST API request limit varies based on the version of Salesforce you are using.
To view the limit for your org, go to Setup, enter "system" in the Quick Find box, then select System Overview.
If you exceed the REST API request limit, you can’t sync and must complete one of the following:
There is a per user, per app, per hour limit for Chatter REST API requests.