Signal corrupted using peak (biquad) filter at low frequencies
Looks a like a typical stability problem with the poles too close to the unit circle. A third octave wide parametric EQ filter at 25Hz sampled at 44.1kHz has a pole radius of > 0.999 so it's getting VERY close to the unit circle. The lower the frequency, the large the pole radius.The pole section alone has a peak gain for more than 110 dB !!!

With the poles so close to being unstable, you may run into all sorts of problem: numerical noise, noise amplification, coefficient rounding or truncation errors, filter topology (do NOT use Direct Form II or transposed Form I), etc.