I don't think expiring options really does much. But 26th sounds familiar, I'm sure bitmex is around that time too (but I think theirs expire in September or August)...? If most exchanges expire on the same date then this could cause issues imo.
There is no Bitmex in this story, and if you click on link in total $1.3 billion in options is distributed between Deribit, LedgerX, OKEx, CME and Bakkt. Let someone correct me if I'm wrong, but Bitmex doesn't offer this option at all?
This could explain why we go sideways, its possible for a price to be pinned to the most profitable area for options to expire I believe that can occur. The tail can wag the dog but it sounds like thats not going to be the case here if they were really so incorrect to be expecting 11k.
As far as I remember, in the past such dates have resulted in a drop in price, but still volatility is present constantly so any good or bad news can be linked to the current market situation. How much this will be the case tomorrow remains to be seen, but I think the effect will still be only short-lived.