Ok this has been talked about many many times, but I just realised that we have an entire volume where they're missing, with the volume cover picture looking like the Strawhat pirates has 6 members now, with Law being one of them. I think when a volume cover is missing half the crew, that's a pretty bad sign.
This disappearance is completely unprecedented both on the number of members being missing in action, and the sheer length of time. It is of course important to note that while they've been gone for over a year in real time, within the OP world however, this all took place in a day.
What's more worrying is as of yet, the rest of the crew don't seem anxious in looking for them, despite how their last known status was them being attacked by a Yonko ship. Of course, I understand that the captain is unconscious, so there's not much they can do, but still, they could at least have talked about them? So here's a series of poll with regards to this.