Ran into this too. Issue is related to some bad minimization.
In js/build/font.js:
icon:i.icons.colorPaletteIcon
should be changed to:
icon:e.icons.colorPaletteIcon
The problem is somewhat similar to the one found here: https://www.drupal.org/project/simple_menu_icons/issues/3439303 🐛 An error occurred during the execution of the Ajax response: LoadJS Needs review
Removing `$build['#attached']['library'][] = 'layout_builder_browser/browser';` on line 224 in BrowserController.php resolves this, so we need to find a way to ensure that the css file not loaded multiple times. Given that layout_builder_browser.css only contains one css rule right now, it is probably safe to remove this line until this is resolved.
I am also encountering this using LBB 1.7 and Drupal 10.3.1.