[2020] You don't earn SCORE by completing events.

I've seen people a little confused on how you earn SCORE, and technically they said:

You will begin “The Legendary Run” at Rank 1, and you can advance your position on the board by earning S.C.O.R.E. through your Daily and Weekly Challenges. These include completing Public Events and leveling up your character.

But the truth is you don't earn score by completing any event. The only way to earn SCORE right now it's by doing the daily and the weekly challenges. There's a weekly that grants you 100 score per 10000 xp gained in the game. And you earn XP by doing events and leveling up which I think that's what they refered to; which in this case is also true.

Edit: People are saying they are getting SCORE at the end of some events, but remember that every event gives you XP at the end, and if the event gives you 1000 XP, and you need 800XP to reach the 10000XP you need, the SCORE will appear on your screen when you earn the XP from the event and might be a coincidence. Of course, if you earn SCORE after the event and you are not even close to 10k then might be a bug.