Hello Grace,
I investigated this and the details of the tasks added to an incident are not directly available in the SecurityIncident table. Unfortunately, the only way I could find to retrieve the Incident Task description details was by using the API.
If would like to have this added as a Feature request, kindly do so by opening a support ticket by following this guidance https://learn.microsoft.com/en-us/services-hub/unified/support/open-support-requests?tabs=existing-support-request-process.
If you find the answer above helpful, please Accept the answer to help anyone in the community who might have a similar question to quickly find the solution.