Is there something limiting the amount of API calls?

I am doing some integration between our in house software and SuiteCRM, I am attempting to synchronize account data from our in house software into the CRM using the v8 REST API and I get through 313 successful API calls to add/update the CRM records but then EVERY API call after that returns the following response:

Response status code does not indicate success: 400 (Bad Request).

I logged the JSON used for the failing requests for the add/update and used them in Postman and they worked just fine…

I initially thought it was some field that may not be properly escaped so I eliminated all JSON fields except the account name and it still does the same thing on the same record.
I double-checked the header values for content-type and accept after logging them during testing and they are both currently application/json.

I finally settled on some type of rate-limiting issue after I restored the code to use all JSON fields that I had removed for the prior testing, then I set up the code to try to add/update only the first 2 accounts that failed, and then when I ran the code both accounts were successfully added/updated at this point.

What am I missing?