Internal Domain
Categories:
If we have a lot of different domains in our product. And we want to treat these domains as the internal domain. We can set up the internal domain in the admin panel.
Setup Internal Domain
Go to the admin panel and click Data Stream, then click your data stream.

Click the Configure tag settings item.

Click the Configure your domains item.

Add all of your domains that you want to treat as internal domains.

Reference
- Google Analytics 4 Tutorial for Beginners (2022) - YouTube
- [GA4] Set up cross-domain measurement - Analytics Help