Why do some challenges provide more points than others, even if the xp and level of the oponents are the same?

Question

Why is it sometimes 32 xp and sometimes 1xp

Answer 1

Because some are good at challenges, win often and get high secret elo rating.

Answer 2

If you complete challenge with your senior level, you will get more XP!! But when you complete challenge with your junior level, you will get less XP!!

Answer 3

Also if you have more progress in the weapon of choice you may be awarded less points for winning.