What does “secondary” stand for here in the error message?

> You have exceeded a secondary rate limit.

Edit and self-answer:

> In addition to primary rate limits, GitHub enforces secondary rate limits

(…)

> These secondary rate limits are subject to change without notice. You may also encounter a secondary rate limit for undisclosed reasons.

https://docs.github.com/en/rest/using-the-rest-api/rate-limi...