It happened to me multiple times, that when I do a moderate number of requests (in a single thread), then sometimes Graph API timeouts, randomly on any call (even after 30 seconds).
example:
GuzzleHttp\Exception\ConnectException: cURL error 28: Operation timed out after 10012 milliseconds with 0 bytes received (see https://curl.haxx.se/libcurl/c/libcurl-errors.html) for https://graph.microsoft.com/v1.0/drives/xxx/items/xxx/invite
Not sure where is the problem, it happened on the AWS, and on my local PC, so I would expect the problem to be with Microsoft servers.
No idea where to report it or what to do.