I got this from Slack Admin Connect Channel and it has worked for us
without having to rollback. For anyone seeing this issue with error code
AADSTS900144 - if you are using Azure as your identity provider, do NOT
define OIDCDiscoveryURL or ROPGDisco...
We are having the exact same problem. Currently, we are rolling users
back to 2.11 and that is getting them working again. Wondering if there
is an update to the config needed that we are not aware of.