If you’re asking yourself “How long are deleted Teams channels retained?” or “For how long can I restore a deleted Teams channel?” you can find the answer relatively quick. But mostly the original source in the Microsoft documentation is missing.
Answer
Deleted Microsoft Teams Channels are retained for 30 days.
Official Source
In https://docs.microsoft.com/en-us/microsoftteams/limits-specifications-teams#teams-and-channels under the table Teams and channels in footnote 4 it’s stated:
Deleted channels can be restored within 30 days. During these 30 days, a deleted channel continues to be counted towards the 200 channel or 30 private channel per team limit. After 30 days, a deleted channel and its content are permanently deleted and the channel no longer counts towards the per team limit.