I found this out only through errors beginning to show up in API responses.

Previously, the following token url worked for getting an access token
https://www.box.com/api/oauth2/token

However, that endpoint is no longer functional as of around 12pm Pacific 1/21/2025

The endpoint in the current documentation however does work:

https://api.box.com/oauth2/token

Just wanted to share in case anyone else runs into this as well as Box provided 0 notification of this change