Seems like they do have rate limits as of now (2022):
According to this page
The throttling limit is set to 250 transaction over 10 seconds. If
this limit is reached in the first few seconds, HTTP error code 429
Too many requests will be returned and transactions will be restricted
until 10 seconds is reached; transactions will then resume again. For
example, if we receive 250 requests in the first four seconds, an HTTP
error code 429 Too many requests - ‘We have received too many requests
in a short duration. Please wait a while to try again.’ will be
returned and transactions will be restricted for the next six seconds
and then resume again.