Additional team and channel-related features and issues within Microsoft Teams for business
Hi Sebastian_365,
This article below explains how pinning works in Teams channels:
https://office365itpros.com/2021/08/23/how-to-pin-messages-in-teams-chats-and-channel-conversations/
"Channel conversations also support pinning. However, unlike a chat, a channel contains multiple conversations (threads) composed of base topics and replies (messages). You can pin a base topic or a reply. In either case, Teams shows the pinned status of the message with an icon. Any team member (including guests) can pin as many messages as they want in a channel.
The icon used to highlight a pinned message in a Teams channel conversation. The icon used to highlight a pinned message in a Teams channel conversation.
Unlike pinned chats, Teams doesn’t display pinned conversations at the top of the channel. Instead, pinned conversations appear in the channel’s information pane. Limited room is available to display pinned conversations, so the information pane features the two most recently pinned conversations."
Hope this helps.
Regards,