How can a particle's position be random and uncertain in quantum mechanics if it is already pre-determined in relativity?

In relativity, to my knowledge, the path of an object is described by its worldline in spacetime, and since time is a part of the spacetime geometry, an object's worldline--in a sense--always exists on this “block of time” as I heard the PBS spacetime say. But in quantum mechanics (the Copenhagen interpretation), I’ve heard that a particle will exist in (superposition of being in) multiple places at once until it is observed and the wave function collapses and it has a single position.

So my question is, how could these two viewpoints be reconciled? Apologies if I got anything wrong.