Affiliate programs are typically more B2B instead of B2C, so some shops might not want regular customers to be able to see the Referrals tab for Affiliates in the portal.
The Referrals tab is only visible if all 3 are true:
It's enabled in the Customer Portal > Customize menu
Store has an active Affiliate app (trial or subscription)
Current user is an affiliate
So it won't be visible to normal customers by default unless they are also an affiliate.
Therefore, if you want to keep the two segmented, we recommend turning off the "Referral callout" which will display a banner on the homepage of the portal inviting customers to become affiliates.
We also recommend ensuring that "Add New Customers as Affiliates" is also turned off so that only the people you invite will be affiliates.