@Georg Künz I was able to get some information on this from the product team.
It doesn't look like it is possible to access the audit logs for legal holds via Azure Portal, but it is supported by the REST API: GetBlobContainersGetWithAllowProtectedAppendWritesAll
Looking at the sample response under Legal Hold, we can see the tags, timestamp, objectIdentifier and tenantId:
Hope that helps.
If you have questions, please let me know in the "comments" and we would be happy to help you. Comment is the fastest way of notifying the experts.
Please don’t forget to Accept Answer and hit Yes for "was this answer helpful" wherever the information provided helps you, this can be beneficial to other community members for remediation for similar issues.