Hello,
Please see a similar thread:
Right now you can only do it directly in the Team (and you cannot see any details on who deleted it, but you can see when it was deleted):
However, you can set up an alert for when a teams channel is deleted. You can use an activity alert policy https://security.microsoft.com/managealerts or set up an activity policy with Defender for Clouds Apps using "ChannelDeleted".
If this is helpful please accept answer.