What determines which winnings will be included in the restricted balance?

Winnings included in the restricted amount of a withdrawal restricted bonus are limited to those winnings that result from the use of the restricted amount (and only if those winnings are to be restricted as per the bonus offer terms and conditions). There is no maximum cap on how much winnings may be restricted. If a player has active withdrawal restricted bonuses where the winnings are restricted, the winnings amount gets added to the restricted balance for that bonus until the bonus release conditions have been met.