Yes, I´ve read the documentation however:
1 - As far as I know there is no way of implementing an exponential backoff algorithm in powerquery; the directions on the doc reffer if you are coding something then you can use that technique in your code;
2 - It used to work fine I've had reports connected to multiple sheets with a large number of rows and it used to work fine. Now for some reason I cannot load consitently even a single small sheet without receiveing this error. Ehich lead me to believe it is somthing inherently wrong with the connector.
3 - Since it is related to the ammount of requests, I believe this is an issue on sheets connector in powerbi it is spamming requests and causing this issue. If it had by itself implemented the algorithm to slownly request instead of just erroring out, I believe it should work.
4 - The ammount of issues from otehr users claimming the same issue leads to believe that this is not an isolated issue, hence an issue with power query.
5 - If you keep on trying to refresh, eventually it will work. So if nothing has changed between refreshes (google did not change the requests limit, the sheets are teh same the tarnsformations in PQ are the same, the users are the same, there is a single user requesting data from that sheet) the only explanation is something worng with how the connector is handling the requests.