Adaptive card extensions do not respect fonts from Brand Centre in some locations

Target SharePoint environment

SharePoint Online

What SharePoint development model, framework, SDK or API is this about?

💥 SharePoint Framework

Developer environment

Windows

What browser(s) / client(s) have you tested

• 💥 Internet Explorer
• 💥 Microsoft Edge
• 💥 Google Chrome
• 💥 FireFox
• 💥 Safari
• mobile (iOS/iPadOS)
• mobile (Android)
• not applicable
• other (enter in the "Additional environment details" area below)

Additional environment details

• browser version: Google Chrome 141.0.7390.108 (Official Build) (64-bit)
• SPFx version: 1.21.1
• Node.js version: 22.14.0

Describe the bug / error

When a font package is created with Brand Center and applied to a site with a Viva Connections dashboard, the font is not applied in some locations for Adaptive Card Extensions.

On the Card View for the Search Card Template, the font is not applied for the placeholder and any typed text for the search box, and the suggestions area at the bottom of the card. This occurs for the OOTB People card as well.

ACE:

OOTB People:

On the Quick View for the Generic Card Template, the font is not applied to any content after the title. This occurs for both ACE and OOTB cards.

ACE:

OOTB Quick links:

Steps to reproduce

1. Ensure the Brand Center has been set up from the M365 Admin Center > Settings > Org settings > Brand center
2. Upload font files to the Brand Center
3. Go to the site with the Viva Dashboard set up and create a font package with the font files
4. Apply the font from Gear icon > Change the look > Font
5. Create an Adaptive Card Extension with the Generic Card Template and deploy it
6. Create an Adaptive Card Extension with the Search Card Template and deploy it

Expected behavior

The fonts from the applied font package are applied to the Search Card search box and suggestions, and the content of the Quick View for the Generic Card Template.