You might think that such an important and long-standing feature as printing would undoubtedly be backed up by a large company. This was true until 2019, when it was backed by Apple. Currently, however, CUPS and all related projects are supported by volunteers, including myself.

Apple abandoned CUPS years ago, and recently have archived the repo on github: https://github.com/apple/cups

All the current development runs in OpenPrinting github: https://github.com/OpenPrinting, and mostly focused on newer projects, such as CUPS v3, PAPPL, Printer Applications.

Recent versions of CUPS v2 are still used in Chrome OS and Chromebooks though (apart from all Linuxes).