From #2940212-12: [meta] Miscellaneous UI issues for the Layout Builder module:
The text "Add Block" is confusing to site builders who are not clear on the difference between custom/programmatic blocks or field content placed as a block. Other projects like WordPress's Gutenburg use a + symbol with the label "Add block" there for accessibility.
The interaction of clicking "Add Section" and then having to go to the right panel to choose a layout, and then having the layout appear on the page, is confusing. Some users click "Add Section" and then scroll down and get lost. Greying out the rest of the page temporarily to show the connection between the settings tray and the page layout would be useful. Something like this:
