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.
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.