It's caused by stick drift, you just don't notice the drift in normal gameplay because your drift is less than the default deadzone setting. However, the spawn screen doesn't respect the deadzone setting, and any small input will cause the cursor to move at full speed in that direction.
Edit: With further experience, I don't think it's caused by stick drift, the cursor just starts in the top left corner.
Nah it's most definitely not. I have tried two controllers, with both TMR and hall effect sticks (which are essentially drift proof) and both have the same identical behavior. My deadzone is also set to 0 and I have no issues in game or in other menus. And even if it was drift, the odds both controllers would have the exact same drift in the same direction in one specific situation is infinitesimally small.
