The whole thing probably depends on the federal state and is determined by the Landesbanken.
What do the Landesbanken have to do with the KFW? You probably mean the development banks of the respective federal states (nBank, NRW.Bank, L-Bank, etc.), which handle the processing for the KFW, right? However, I am not aware that they set any rules for this, especially since there is no release from liability for the classic subsidies for private individuals (124,151,153...).
How the bank on site designs and determines the conditions (and that's the only thing this is about) is up to each bank itself.