  Coalescing binary black hole (BBH) systems are likely formed via several
channels, and it is challenging to understand their formation / evolutionary
processes. Some features in the mass function of the primary components
($m_1$), such as the distinct Gaussian-like peak located at $\sim 34M_\odot$,
have been previously found. In this work, we investigate the possible
dependence of the mass ratio ($q=m_2/m_1$) distribution on the primary mass. We
find a Bayesian odds ratio of 18.1 in favor of divergence in the mass ratio
distributions between the low- and high-mass ranges over an invariable mass
ratio distribution. The BBHs with $m_1\gtrsim29M_{\odot}$ have a stronger
preference to be symmetric compared to those with $m_1\lesssim29M_{\odot}$ at a
97.6\% credible level. Additionally, we find mild evidence that the BBHs with
$m_1$ located in the Gaussian-like peak have a mass ratio distribution
different from that of other BBHs. Our findings may be in favor of some
formation channels, such as the chemically homogeneous evolution and the
dynamical assembly in globular clusters/nuclear star clusters, which are more
likely to provide symmetric BBHs in the high-mass range.
