The vast majority of Slack's interface is buttons and clickables, and really no links at all, except for in specific messages.

However, all the messages are within an ARIA application, which means that NVDA does not render this in browseMode, rather when focus goes inside the application, focus mode is used. This also therefore means that those links will not appear in NVDA's elements list.

The exception to this is when arrowing down to a particular message and then pressing tab, focus moves inside a document specific to the current message, and therefore browseMode can be used, though bounded only to that message content. Within this particular subdocument, NVDA's elements list can be used, and any links in that specific message will be listed.

The ARIA application around the message list was introduced sometime last year in the Slack app, so none of that is new, unless you happened to be using an old version of the app until just recently?

Regards

Quentin.