The feature isn't new by itself but still recent and not obvious to discover. It turns out that as soon as you like a certain post on your feed, Linkedin will show you a car with smart suggestions that are supposed to encourage you to start a conversation. Normally it will contain some text snippets like "Nice!", " Well said" etc.
How to test:
- Like any post on your feed.
- Check a new bar with smart suggestions below.
- Tap on any suggestion to add this text to the comment box.