As I understand it, many ships are choosing not to make the trip for the time being. Iran attacked a bunch of ships, and sank one (a UAE tugboat, if Wikipedia is to be believed), but Iran hasn't hit another ship for a couple days (perhaps no ships are traveling through right now?). I suppose it is possible that the maritime situation there will ease up if passage is tested, and Iran is not able to hit any ships. But, I can see how Lloyds of London might not think the trip is 100% safe...nothing is ever 100% except in the political arena where each side requires the other side to be 100% perfect.
(I am definitely not an expert, so if someone else can chime in with better information, I will defer to them.)
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