I will also echo the sentiment that I’m very frustrated by the lack of appropriate communication here. Our product did use this API but we have the luxury of being able to migrate to the GET endpoint.
A forum and blog post is not an appropriate communication mechanism for breaking changes like this. Our product is huge and interfaces with a dozen API providers and it’s impractical for us to be checking the every provider’s blog/Twitter/forums. The bare minimum here should have been proactively sending an email or two.
This last point is less egregious and more open for debate, but I also believe in inappropriate status code was chosen when deprecating the endpoint. HTTP 410 would’ve been my preferred choice given that returning 404 was a valid and acceptable response when the endpoint was working. I acknowledge that we should have been matching on specific messages rather than purely the status code, but handling this better would’ve reduced our troubleshooting time greatly.