If your Funnel Workspace was created before May 2019 there was an "Ad platform basic" metric group:

This has been upgraded and it is now possible to see how each normalized metric (Cost, Impressions, Clicks, CPC, CTR, CPM) is calculated:

It is also possible to edit these calculations in case Funnel's standard definition does not represent your setup.
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From a technical point of view, this means that the "Ad platform basic" metrics, which where a special type of metrics, have been migrated to become custom metrics.

This migration means they will be grouped with other custom metrics and have the same icon as them:

No action is required since the metric IDs do not change. Due to this so you should not expect any changes to your data flows.