Okay, sounds like it was decay then and someone tore it down (not Funcom, a player). Your logs would show this if you looked. When Funcom bans a player, they don’t tear down anything, it simply decays like it always does.
And they have never had MMO support to reimburse lost items. That’s never been the case since 2017.
People also do not get banned for simply logging in to refresh their decay timers. Either they or someone in their clan did something against the rules and got caught. Perhaps it was not the OP, but someone along the line did and thus the ban was put into place. Call me cynical but I’ve seen too many post of “I’ve been banned for no reason” only to have it come out they were banned for a very valid reason all along.
Also, Are you on a pvp server? You said you have two buildings, and the main one is safe but the other is gone? Maybe it got destroyed by another clan? Maybe it was decayed and destroyed by other players that way like @Multigun said. There are far to many factors at hand and not enough actual information to actually know what is going on.
Extremely doubtful. There is a far better chance that the user joined a server that “looked official.” There are numerous private servers that try to disguise themselves as officials to get people to join.
Yeah even though you can see if they have the official checkmark, I only noticed that because 2 servers with the same name randomly popped up in the list right next to each other (one official one not).