Hi @luca1 ,
Thanks for sharing details on your setting!
Based on my further investigation, I would say there is no expected time to response as this is really quite multi-factor thing. It’s explained here.
When it comes to your use case, a factor to investigate might be the limit of active (valid) refresh tokens per user per application.
We have an article on performance best practices.
There is also option to perform load test and share it via support ticket (for customers with subscription allowing them to contact Auth0 support center) - this way, knowing the specific circumstances, Auth0 engineers can investigate it further. The proces is described here.
I can see you have opened a support ticket on this problem, and I belive it’s best to continue there as via a support ticket you can share information, that due to security considerations, can’t be shared here.
I remain available in case of follow up questions.