Thank you for reaching out.
I understand that your concerns regarding Guest account cleanup activity using Microsoft access review, Stop an Access review instance and the option for recovery for the deleted access review.
In the guest account cleanup activity yes, you are correct, the created access review series action is got applied. If the access review is already completed or stopped, you won’t be able to restart.
Reference: https://learn.microsoft.com/en-us/graph/api/accessreviewinstance-stop?view=graph-rest-1.0&tabs=http
https://learn.microsoft.com/en-us/azure/active-directory/governance/complete-access-review
In the process to stop the access review the STOP button is greyed out it could be because of the access review is already completed or the access review has already been stopped.
The option to recover the deleted access review is currently not available in the Microsoft Entra ID. because delete access review is type of hard delete.
Reference: https://learn.microsoft.com/en-us/azure/active-directory/architecture/recover-from-deletions#audit-log
How ever you can share your feedback on recovery of access review via https://feedback.azure.com/d365community/forum/22920db1-ad25-ec11-b6e6-000d3a4f0789 which is closely monitored by our product team.
Let me know if you have any further questions feel free to post back.
Thanks
Akhilesh.