At beginning of year, a player (with what seemed as a new account with a level skip) created the fc I entered 1 week after that. FC leaders told members they could complete "tasks", that were voluntary activities, all of them were centered on getting stuff to put in fc chest. That will made them earn higher rank in FC. The tasks at lower rank were simple stuff like "give xx of every shard to chest", and at higher rank were "do this stuff to get some items and put them in chest" (another member told me it took him hours to do that). I was keeping record and donations to chest between gil and shards (at market board price) were some millions of gil (I never donated anything neither did the tasks, I just stayed there to chill with people). And told the people in top ranks will get rewards in gil. At end of first month they gave rewards to people in highest ranks, like 8 millions gil in total, but it was not even close to the value of everything gathered in chest. One day they even told members that for every new member they got during that day, they would receive 100K gil, they got almost 130 members at 5 weeks after fc creation.
I left 1 month after entering the fc (just after other members left saying everything in the fc was a scam). I told in chat that if everything wasn't a scam, leaders should put everything clear, like saying in discord the total monthly income, so everyone would know how is their money moving. And if it was, indeed, a scam, I hoped there were not more people caught in that. Some hours after that the leader send me a /Tell saying she was gonna report me for harrassement. She didn't do it.

After that the member numbers dropped to 60 and stayed like that. But some months after that one of the leaders "sold" the fc to other player and only after that, they told the rest of the current members via discord.
So at the end, the leaders got lots of millions of gil for "donations", and some more for selling the house, at expenses of the members who donated voluntarily doing stuff that took hours.
The new fc/house ownder said they don't know anything regarding the actions of the old leader. They changed the name and have been using it for a small number of friends.

Today I saw one of the former leaders in limsa /shouting inviting people to her fc, that has the same name as the older one, it was created 5 days ago and they have 20 members, but there isn't any of the old members that were inside it until it was sold (like the members are dispensable gil-makers).
It's obvious that what they're doing is wrong, and it's highly probable they wanna grab a lot of the new players that are starting playing the game those weeks, maybe (maybe not) to do the same gil-grabbing scheme.

But I don't know if the actions of both leaders are bannable/reportable or not.