Failure applying theme styles results in a lack foundational block styles

[dcalhoun]

Description

Some block types lack foundational styles when the theme styles fail to apply. E.g., the Gallery block does not display its media items in a grid, but instead displays them stacked in a single column. It is unclear what leads to failures, but we should better handle that scenario.

Step-by-step reproduction instructions

Unknown.

Expected behaviour

By default, the photos are displayed in two columns.

Actual behaviour

The photos are displayed in a single, stacked column.

Screenshots or screen recording (optional)

WordPress information

• WordPress version:
• Gutenberg version:
• Are all plugins except Gutenberg deactivated?
• Are you using a default theme (e.g. Twenty Twenty-One)?

Device information

• Device: iPhone 15
• Operating system: iOS 18.3
• WordPress app version: 25.7.1