Search for missing data starting with certain text

Hello I need to compare two columns and output all missing data into a third column.

The problem is that I need to also filter the first column for only certain cells that start with two letters

This is what put together and was expecting to work but I am not sure whether I am using incorrect formulas or the identificator for the starting text is not working..

=ArrayFormula(FILTER(D3:D;ISERROR(MATCH(REGEXMATCH(D3:D;"MY.");A2:A;0))))

• Column "D" contains all data to be filtered
  • it contains cells starting with "MY", "NY", and "FY"
• Column "A" contains all data to be compared to
  • this one may be missing some cells "MY...." and that is what I need this formula for