As of now, the behavior of Expand, Show details, or View in the Assist app is inconsistent.

The fields they show change (there are situations where a field may or may now show) and it's not possible to customize it. Their behavior does not match the request form or work item view configured in Jira. 

This can be cumbersome, as the user then needs to leave Slack/Teams to review information via portal. For example, without showing the right fields, having the approval step in Chat loses some its value.