Description

When assigning the underline styling to the overall navigation block, the "optional placeholder" text adopts the underline likely due to some CSS bleeding.

Step-by-step reproduction instructions

1. Add a navigation block to the site editor.
2. Add a search block.
3. Select the overall navigation block and, in the sidebar settings, select the underline option.
4. Notice that the "optional placeholder" text shows underlined text.

Screenshots, screen recording, code snippet

Environment info

• WordPress 5.8
• Gutenberg 11.3
• Desktop with MacOS

Pre-checks

• I have searched the existing issues.
• I have tested with all plugins deactivated except Gutenberg.