This feature lets you view all the chats pinned in a channel.
How it works:
Go to the channel, whose pinned chats you wish to view. Click on details option and then on pinned chats option to view all the chats pinned in that channel.
Pinned chats in a channel-
Viewing pinned chats serves the purpose of keeping all the important pinned chats of a channel at one place and easily accessible whenever required.
Viewing pinned chats help you look every chat that was considered enough important to be marked in a channel, If you loose out on an important message even when it is pinned, you can find that message using this feature.
Watch this video to see more in details - https://youtu.be/IFvDYUd04DY