Problem/Motivation
In #3087701: Enable Claro as the admin theme in Umami we enabled Claro as the new admin theme for Umami. In there we added the Theming Blocks config to the core/profiles/demo_umami/config/install directory.
In #3278565: Remove Claro block configuration from Standard we removed those blocks from the Standard profile, because those blocks config are already present in the core/themes/claro/config/optional directory.
Proposed resolution
Since Claro already ships with its block configuration, we should be able to remove the block configuration from Umami.