A new config schema data type has been added: required_label.
All config entity labels have adopted this new config schema type for their labels. (This is one of the many steps along the way that will eventually allow validating config entities.) The only exception for now: Views, which is still being worked on in #3380480: Views should require a label, rather than falling back to an unhelpful ID. Some other labels are also required, for example the "on" and "off" labels for boolean fields, and these have also adopted this new config schema type.
Note: There's no disruption for config schemas switching from type: label to type: required_label, because config schema validation is not yet being used.
Historical Context
#1905152: Integrate config schema with locale, so shipped configuration is translated introduced the translatable config schema property. It marked type: string not translatable and type: label translatable.
"Labels" were defined as Human readable string that must be plain text and editable with a text field.
. This type is primarily used for e.g. config entity labels, and as labels for sequences/mappings. In some cases, they MAY be empty (for example: an optional prefix/suffix for a field), but in other cases they MUST NOT be empty.
