Well in the "Pass Access" FAQ section, it does say this:
Are reservations required to ski or ride at any Ikon Pass destination?
Lift reservations to ski and ride may be required at certain Ikon Pass destinations during the ski season to help manage capacity and improve the guest experience. The decision regarding whether reservations will be required for any winter season are made at the discretion of each Ikon Pass destination and will be based on circumstances at the time. For the 21/22 winter season, lift reservations are required at Jackson Hole Mountain Resort, Taos Ski Valley and The Summit at Snoqualmie. For the 22/23 winter season, lift reservations will be required at Aspen Snowmass, Jackson Hole Mountain Resort, Big Sky Resort, The Summit at Snoqualmie, Loon Mountain, Taos Ski Valley, and Brighton Resort.
And there were reservations required at some resorts this year as well. Looks like that's somewhat expanded for next year. I have not heard of anyone having any issues getting a reservation - but don't know many folks that ski at the absolute busiest times or don't reserve early. That said, the existence of reservations always means there's some chance of not being able to get one. I suspect that that's only likely on the busiest days if you don't reserve in advance.