Starting on January 20, 2025, new Performance Max (PMax) campaigns created with the UI will have brand guidelines enabled and require business name and logo brand assets to be linked at the campaign level rather than the asset group level. Brand guidelines  is a new feature that allows you to control how your brand is represented in your Performance Max campaign automated assets or formats.
What this means for API users 
New PMax campaigns created in the UI with brand guidelines enabled will automatically link BUSINESS_NAME LOGO LANDSCAPE_LOGO CampaignAsset AssetGroupAsset Campaign.brand_guidelines_enabled 
As of v18 of the Google Ads API, it is not possible to create brand guidelines-enabled PMax campaigns via the API, which means new campaigns must link BUSINESS_NAME, LOGO, and LANDSCAPE_LOGO assets using the AssetGroupAsset resource. In a future release, you will be able to create and fully manage PMax campaigns with brand guidelines enabled.
It is important to note that the same asset requirements  will continue to apply to all PMax campaigns regardless of whether or not brand guidelines are enabled. However, BUSINESS_NAME, LOGO, and LANDSCAPE_LOGO asset requirements will be evaluated at the campaign level for campaigns with brand guidelines enabled and the asset group level for campaigns without brand guidelines enabled. You can reference the relevant section of our Performance Max optimization and troubleshooting guide  for more information, and as always, contact our team  if you need support.