Keys of Classic Application Insights:


- In your
Application Insights => Properties => Under WORKSPACE => click on Migrate to Workspace-based.

- Select the
Log Analytics Workspace which you have created in the first step = >click on Apply.

You can see the warning that once migrated to Workspace-based, again cannot migrate back to the classic Application Insights.
Even I didn't find any option. We have only option to change it to another Workspace.

- Keys after Migrating to
Workspace-based.

I dint find any changes in the Instrumentation Key and Connection String.
As mentioned by @ZakiMa, yes there will be no changes in the Instrumentation and Connection String Keys.
- New Key with
WorkSpace name is added.

impact of migrating classic Application Insights to workspace-based Application Insights resources
Data is not transferred from classic to the Workspace-based Application Insights Instance.
As mentioned in the Document,
There will be no impact on our Live Metrics or AppInsights Monitoring.
References taken from MSDoc.