Google has updated its documentation to indicate that Performance Max campaigns may filter out navigational and brand-specific searches in favor of dedicated brand Search campaigns. This change ensures that brand-related queries are managed by campaigns offering more precise control.

The updated help page advises advertisers to ensure their brand Search campaigns have adequate budgets and high-quality ads to capture this filtered traffic.
Additionally, incorporating Search Themes into Performance Max campaigns may help in aligning strategy.
Read the official help page here: How Performance Max interacts with other campaigns in your account.
This update was spotted by Hana Kobzová.