Property pane titles are not translated

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 140.0.7339.185 (Official Build) (64-bit)
• SPFx version 1.21.1
• Node.js version 22.14.0

Describe the bug / error

Even if the title that appears for the property pane is provided in multiple languages in the manifest, it still appears in English when editing the web part as a user with a profile language set to one of the translation languages.

Steps to reproduce

1. Create a new SPFx web part using the Yeoman generator
2. In the preconfiguredEntries of the manifest under "title", add the translation for the title in a second language, Ex: "title": {"default": "Sample", "fr-FR": "Échantillon"}.
3. Build and package the web part.
4. Deploy the web part to a site and add it to a page.
5. View the page as a user with French (France) as their language. The property pane title will display in English.

This also happens with out-of-the-box web parts like News (Shows "News" instead of "Nouvelles"). The description works as expected, only the title is not translated.

Expected behavior

If a translation is provided in the web part manifest for the title, it should be shown when viewed by a user with that language set in their profile.