Keepit backs up the following standard channel tabs in Microsoft Teams: Website, Planner, Word, Excel, PowerPoint, Visio, PDF, Document Library, OneNote, SharePoint, Stream, Forms, Power BI, Flow, and Azure DevOps.

When a channel is restored, the tabs are returned to the top of the team. The tabs will always be restored even if the entire team, channel, or file (the original file of the content that is embedded in the tab) has been deleted. The only exception is the Azure DevOps tab: If the team was deleted, the tab will not be restored. 

What happens to the embedded content when the tab is restored?

Planner
In all cases, only the tab will be restored. Content will not be embedded in the tab.

Word, Excel, PowerPoint, Visio, PDF, OneNote, Forms
The tab is restored with the embedded content.
If the file or channel was deleted, the tab will be restored without the embedded content.

Document library, SharePoint, Stream, Power BI, Flow (Power Automate)
The tab is restored with the embedded content.
If the entire team was deleted, the tab will be restored with the embedded content. 
If the file was deleted, the tab will be restored without the embedded content.

Website
The tab is restored with the embedded content.
If the entire team was deleted, the tab will be restored with the embedded website content.

Azure DevOps
The tab will not be restored if the team was deleted.