13 hours ago
@mentions in comments is in development currently and as per current status it will be available soon (January CY2021 release)!
You can also get the comments using SharePoint REST API - Not sure if this will help you. But, you can check if you can do something with this REST API using Power Automate (or you can wait until above feature gets released).
Check these all details at: SharePoint Online: All you need to know about Commenting in Lists
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