Asana
Historical free collaboration shrinkage
Asana's 2020 SEC filing says it offered a free Basic version for teams of fewer than 15 people and a free Basic offering for teams of up to 15 people. Current official Asana Personal and pricing pages describe the free plan as for one or two people and list up to two users/seats per project and team.
Campaign angle: An Asana alternative for small agencies and founder-led teams that need a shared project workspace for 3 to 15 collaborators before paid project-management seats make sense.