Dominant Pole Approximation
Your circuit features 3 capacitors but is actually a 2nd-order system (degenerate case). The denominator of the transfer function (whatever it is) follows the following formalized form: \$D(s)=1+\frac{s}{\omega_0Q}+(\frac{s}{\omega_0})^2\$.

In this expression, \$Q\$ represents the quality factor and illustrates the losses in your circuit. Because \$D(s)\$ is a 2nd-order expression, there are two roots or poles. Depending on the value of \$Q\$, we can distinguish three scenarii:


\$Q\$ is large, greater than 0.5: the poles are complex conjugate, the time-domain response is a damped oscillatory waveform.
\$Q\$ is equal to 0.5: the poles are coincident, the roots are real (no imaginary term) and the response to a step input is fast, without oscillations.
\$Q\$ is small, much lower than 0.5, e.g. 0.01 for instance: the poles are real and well spread from each other. In this case, the denominator can be approximated - hence the term associated with this arrangement: the low-\$Q\$ approximation - to two cascaded poles: \$D(s)=1+\frac{s}{\omega_0Q}+(\frac{s}{\omega_0})^2\approx (1+\frac{s}{\omega_{p1}})(1+\frac{s}{\omega_{p2}}) \$. In this mode, it is easy to show that \$\omega_{p1}=Q\omega_0\$ and \$\omega_{p2}=\frac{\omega_0}{Q}\$. If \$Q\$ is really small, then you naturally see that \$\omega_{p1}\$ is lower and dominates the low-frequency response while \$\omega_{p2}\$ is higher and can be neglected provided the high-frequency response is of lesser interest.


If I had to analyze this circuit, I would recommend the usage of the fast analytical circuits techniques or FACTs which will let you obtain a low-entropy transfer function in a flashing time.