Excel - Graph API rate limit give 429 with just 5 request per second

Question

As per the document https://learn.microsoft.com/en-us/graph/throttling it is mentioned that excel API has a rate limit of 5000 request per 10 sec

But when we tried the below Range Object API which is POST request we get 429 error just with 10 request per second. Which is very low as compared to 5000 request per second as mentioned in document.
Can you please let us know why we are getting 429 error with just 10 rps

https://graph.microsoft.com/v1.0/me/drive/root:/sample.xlsx:/workbook/worksheets/{00000000-0001-0000-0000-000000000000}/range(address='A38:GU40')/insert