It appears as though Walt Disney World has increased the capacity for this year's Halloween hard-ticketed event.
As of Thursday, Disney After Hours BOO BASH tickets were sold out on 8/10, 9/21, 9/24, 10/5, 10/8, 10/10, 10/12, 10/15, 10/19, 10/22, 10/26, 10/29, and 10/31/21.
At the time of this post, the only dates listed as sold out are 8/10 and 10/31 which indicates that the event's capacity had to have been increased.
We don't know the inside details of how many tickets were originally sold, so we can't say what kind of difference this will make regarding how light the crowds will be during the events. If Disney only sold up to 30% worth of tickets for one of their typical "After Hours" events, it would make sense that with COVID restrictions easing up, they'd increase that number. It doesn't mean the event will be increased to the capacity of Mickey's Not-So-Scary Halloween Party, however; that remains to be seen.
In the meantime, if the date you were looking to attend the event was previously sold-out, tickets can be ordered by calling (407) 939-4240 or through your Dreams Unlimited Travel Specialist as part of your package/room reservation.