>>214222636 (OP)
A flop? Ehh... a flop is a high bar, it needs to be or else the term means nothing.
A significant disappointment? Definitely.
The Fantastic 4, along the X-Men were the only new Marvel characters that anyone gives a shit about that Disney hadn't already used.
So this movie mostly flying under the radar, and for the first time losing out to their DC competition is a major issue for Disney and the MCU moving forward.
Disney has pinned much of their hopes of the future of the MCU on this film, so it doing pretty mediocre, not much better than the previous flops, is very bad.