The base is 10% and the way it works is (at least worked previously) that if one side has a lot more people in warmode then this 10% bonus is going up to 15-20-25% and so on and at some point when it is way too unbalanced there is an extra weekly quest I believe at 25%.
Now it is highly unlikely that both alliance and horde has roughtly same amount of people enlisted given the fact that there is like a 90-10% ratio in favour of horde.
Perhaps it is frozen to 10% so alliance can’t get the extra weekly? What happened with this? Maybe not in effect for the first week or was it changed?
A very important issue you’re raising!
I recently returned to the game and it is virtually impossible for an Alliance player with WM on to get a quest done, especially the world bosses and the big ones. The Superbloom is overrun by Hordes with a couple of Alliance players trailing the Ancient in stealth, pitifully trying to get the rewards.
They really need to give us the 15-20% Warmode rewards; I recall when they increased the bonus in BFA, so many Alliance players turned it on and started making WPVP a lot of fun.