You’re totally right! I revised my schematics in the meantime and forgot to report the changes on this forum. I swapped C8 with C9 (220 pF / 1 nF) to take into account the high impedance of the input and added a 2M2 resistor tied to ground just before C7.
I will fix the 100 nF output too. I forgot that people may want to plug their pedal directly on regular line inputs.