Refunds only apply to multi-user lots as the deposit size for a challenge lot is determined by the lot creator.
As the lot creator only decides their own deposit size in a multi-user lot, it may be the case that the deposit pools for Asset A and Asset B are imbalanced (for example if 2 users deposit 10$ each on Asset A but 3 users deposit $10 each on Asset B).
In such a scenario, the pools are balanced to equal size prior to a lot going live. Users with positions in the excess pool will be refunded the excess deposit amount in proportion to their deposit size.
refund(user) = position_size(user) / pool_size * (pool_a_size - pool_b_size)