"This subreddit was banned due to being unmoderated." This just means that whoever had control of the subreddit has deleted their account or not logged in for

"This subreddit was banned due to being unmoderated." This just means that whoever had control of the subreddit has deleted their account or not logged in for 90 days. It happens automatically to prevent abandoned subreddits from filling with spam. There are 2.8 million subreddits so this is going to happen hundreds of times a day. There is a process for people to ask to take control of an unmoderated subreddit, you just post to r/redditrequest and wait two weeks.