The strange thing about this error is that it can appear, even when we're not carrying out activity that takes us even close to the Graph API service limit. For example, the Excel limit is 5000 requests second per 10 seconds across a tenant.
There appears to be very little detail on this error, although there are some reports from users who have seen this issue from Power Automate.
I suspect the cause of this problem is a service or network issue that temporarily prevents the connector from reaching the data storage (eg, OneDrive/SharePoint). The connector then retries until it exceeds the Graph API limit.
Whilst there is no fix to this error that I'm aware of, I have found that the connectivity to Excel resumes after waiting some time. This could be 30 minutes or so.
I imagine that most users never encounter this issue However, it is something to take note of if you choose to make heavy use of Excel with Power Apps.