Microsoft.SecurityInsights api-version 2020-01-01 suddenly unsupported

Hi all,

I use a Sentinel playbook to automatically close certain alerts. At a certain point, I use this endpoint: https://management.azure.com/subscriptions/[subscriptionid]/resourcegroups/[resourcegroupname]/providers/Microsoft.OperationalInsights/workspaces/[workspacename]/providers/Microsoft.SecurityInsights/incidents/[incidentid]/relations?api-version=2020-01-01

Since 2 weeks or so, this playbook fails with the error "BadRequest". It gets a status code 400 with a json, with code "UnsupportedApiVersion".

I've been googling for a while now, but can't find much info about these endpoints or the reason it doesn't work anymore.
This leads to a few questions:
- what happened with api version 2020-01-01? (https://github.com/Azure/azure-rest-api-specs/tree/master/specification/securityinsights/resource-manager/Microsoft.SecurityInsights/stable/2020-01-01 still seems to exist and is unchanged for months)
- how can I find out the correct version?
- where can I keep track of changes like this?

Start with specification/securityinsights/resource-manager/Microsoft.SecurityInsights/stable/2020-01-01 and the reported relations endpoint. Compare that specification with the service's currently supported API versions and review the repository's API-version change guidance. Done means the supported version and the source of the change are identified and recorded clearly.

Written by the indexing model from the issue text.