This level of uncertainty doesn't require FTL, only a lack of faster-than-you communications. When you crossed the Atlantic in the early 1800's to visit an ailing grandparent, you didn't know if they'd, say, die during your trip, until you got there. Or if they'd moved to another city with a better hospital.

There are scenarios that are specific to FTL information transmission though; If we believe FTL is possible, under our current model of relativity we have to believe that FTL messages can travel backwards to earlier on our timeline, breaking observed causality:

https://en.wikipedia.org/wiki/Tachyonic_antitelephone#Numerical_example_with_two-way_communication

https://worldbuilding.stackexchange.com/questions/46873/are-there-any-ways-to-allow-some-form-of-ftl-travel-without-allowing-time-travel