What is this view being used in my query?
Views starting with VW_DTP showing up in the execution plan is the result of one of the cost-based query transformations available since 11.2, called distinct placement.

It happens with statements using the DISTINCT clause, just like yours. It is an absolutely acceptable an quite obvious execution plan to join the tables and filter the rows, and after that, find distinct rows. However, finding distinct rows at the time of accessing the tables, before joining them, may be more effective, and the database may choose to transform the query based on the estimated cost.