How is Project Finish Date derived (month, day, years) if left blank when creating a project?

Summary:

Observation:

Year - 34 years is derived based on the difference between Project Task Finish Date - Project Task Start Date

Month & Day - When project is created from Template without Project Finish Date, system is calculating 2 days less than Project Start Date as the default Project Finish Date. What is the basis of this / how is it being derived?

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Version (include the version you are using, if applicable):

Release 23D

Code Snippet (add any code snippets that support your topic, if applicable):