It specifically sets the grandfather date to the project application date - so if I roll into your town and submit a proposal for a building, you can't tomorrow add a "hendrikrassmann law" that requires me to do something additional.

Note that this is NOT the case usually - if you propose a building today and construction starts in 4 years you often have to code-update everything to the construction start date; or even the construction end date. So the law has a purpose.