We are an enterprise open-source software company.  Our software is user deployed, either on-premises or in the cloud.  We use Slack for our frontline support channel with customers.  With those customers who have their own paid slack workspaces, we create a shared Slack channel between the two workspaces.

The Zendesk Slack application cannot be added to those shared channels.  It limits the usefulness of Zendesk to us, as most support tickets start as a Slack conversation and are then escalated into a ticket.

Shared Slack channels are a new-ish Slack feature.  I'm sure we're not alone in using them this way.