The Edit menu for many Looker visualizations contains the Show Full Field Names option. In Looker 6.8, the default setting for this option has changed to OFF. Only the field names show in visualizations (in the case of count
measures, the view names show):

In prior releases, Show Full Field Names defaulted to ON and both the view names and field names were shown in visualizations:

Turning on the Show Full Field Name legacy feature instructs Looker to use the old default of view name and field name. By default, this legacy feature is off, and it will be removed in Looker 6.12.
Regardless of the status of the Show Full Field Name legacy feature, users can always choose whether to show the full or shortened field names by adjusting the Show Full Field Name option in a visualization’s Edit menu.
For a complete list of legacy features and when they’ll be removed from the product, see the Legacy Features End-of-life Schedule.