Hello,
The wiki was marked as inactive and closed due to a Miraheze bug. They do not know what the issue was yet and this has been happening for about two weeks on different wikis hosted by them. This may happen again and if it does, then please @ mention me or @grahamsh so that we can reopen it. Thank you.
"We think we've resolved the closing of wikis by accident. Please do report if you continue to have the issue." -Miraheze