Here’s an overview of the data types that Pro Backup can restore for Slack.
Messages - When you restore a message, the message will be created as a new message at the bottom of your channel. The following data will be restored:
Messages with their formatting, attachments, threads including all thread messages
Note: Emojis posted on a message will not be restored 🤷♂️
Channels - When you restore a channel, a duplicate of the channel will be created in the related workspace. All messages, files and custom fields will be restored as well.