Spoilers for the plot of What if..? episode 8
In the 8th episode of what if...? (What if Ultron won), Thanos comes to earth with all the infinity stones except for the mind stone. Vision then kills Thanos and gets all the rest of the infinity stones.
But how did Thanos get the soul stone? In a later scene in the episode, we see Ultron conquering the universe and he gets to the Sovereign. We see there the guardians of the galaxy (including Gamora) fighting his androids.
So A: How did Thanos know where the stone is? In the movies, he gets Gamora to tell him where the stone is. How does he get the information this time? And B: who did Thanos sacrifice to get the soul stone if Gamora is alive? I don't think there is anyone else he loves or any other way he could've done it.