IRL, a four year old social app, appears to be a fast-growing alternative to Facebook and messaging app Discord. It enables young people to chat in groups about shared interests, such as book clubs and sports, and to plan real-world events around those interests.

In conversations with the press and IRL’s investors, CEO and co-founder Abraham Shafi said the app has 20 million or so monthly active users, nearly double the figure from a year ago—shortly before SoftBank privately valued the company at $1 billion in a $170 million funding round. IRL, which stands for In Real Life, recently shared another impressive statistic with investors: 63% of the people who have begun using the app since the fall of 2020 are still using it as of April of this year—a remarkably high figure for the industry.

But inside the company, some employees recently expressed concern to managers about the usage figures the company has touted, according to two people with direct knowledge of the situation. The issue seems to stem from Shafi’s use of a more expansive definition of active users than that of established social apps like Facebook, as well as emerging ones. These people told The Information they felt the company may have used an unconventional definition to make the app appear bigger than it is. Meanwhile, measurement firms such as Sensor Tower, which estimate app usage by tracking groups of mobile app users and other methods, show IRL has between 1 million and 2 million active users of its mobile app on a monthly basis.