Released in version 1.5 (14 February 2020)
This is likely a bug and should be changed.
According to the java documentation for date formating and parsing https://docs.oracle.com/javase/8/docs/api/java/text/SimpleDateFormat.html:
Lowercase “dd” stands for day of month, but uppercase “DD” stands for day of the year.
Although there are valid use-cases for the latter the lowercase version is used much more often.
Noncompliant example:
parseDateTime('2015-05-21', 'yyyy-MM-DD')
Compliant example:
parseDateTime('2015-05-21', 'yyyy-MM-dd')