It appears this firmware is needed for compatibility with HikCentral 1.1.1 (see http://oversea-download.hikvision.com/Uploadfile/Soft/HikCentral V1.1.1/HikCentral V1.1.1_Compatibility List of HIKVISION Products_20180106.pdf).
This is the only doc I found which bears references to this new firmware.