I always wondered how FJ connect multi accounts, just recently my account was banned, I was accused of having few accounts and after very quick chat with support my account has been unbanned. I suspect it was false positive IP, however, they never said what was the reason.
Did they say anything to you? If there was breach of ToS they should return you your funds.
happened with me as well but after long chat with support they unbanned my account
my case was different since I had a friend who I was sending him my tennis plays mainly and some football , so he was betting the same things that I do
both accounts located in the same country , both accounts starts with the username Dr and both accounts share a lot of similar bets
so they were flagged but after chatting with support and explaining that both of our bets combined don't exceed the limits so makes no sense to multi account especially that I didn't have him as a referral and both of us didn't use any bonus except the mines on the sportsbooks ( which has the same odds if you are multi accounting or not as long as the bet doesn't exceed 20 mbtc ) they unbanned both of the accounts
I talked about it here before but since someone else is having similar problem and you mentioned it as well I thought about bringing it back again
overall support seems to be reasonable and unless there is something extremly fishy all should be fine
the weird thing is that this guy only won 0.015 BTC so not sure what's going on exactly since abusers tend to bet heavier