"Show All Updates" link Salesforce Chatter Feed

If Feed Tracking is enabled for an object, then old value and new value are displayed as the Chatter Feeds.

If there are more than two feed-tracked field  values changes in one single transaction, then it displays a "Show All Updates" link. If you click the "Show All Updates" link, then it will display all the field values changes.

Show All Updates link is shown since it has more than two fields values changes in one single transaction.