I wanted to give a heads-up that Google is officially deprecating key GTFS reference content hosted at https://developers.google.com/transit/ in favor of equivalent resources at https://gtfs.org/. Under the stewardship of MobilityData, gtfs.org has increasingly become the canonical resource for the GTFS spec. We believe it's in the best interest of the ecosystem to drop our own equivalent pages for the sake of clarity.
We have added notices to a number of our pages (see full list below), noting the pending deprecation. In a few months time, we will add permanent redirects for these pages to their gtfs.org equivalents. If you have any questions or concerns about this migration, please reach out. Thanks!