After having revover a normal behavior for EIB, we checked the signals of the injection. It appeared that the beam was quite low on the IBJM quadrant, also low on B1p. This makes sense since we had to lower it to recover the alignment.
We brought the EIB Tx set point back to -600 urad as it was before the noise could appear (it had been set to -525 urad on tuesday).

We slightly adjusted the setpoint from -600 urad to -596 urad to recover the same position on the IBJM_v quadrant. By taking a closer look now it seems that we can still improve it (figure 1). We may want to do it in the coming days.

The IMC followed and went back to the position it had before the noise could appear.
The excess of noise that could be seen in the last two days disappeared. See RFC signals before the noise on EIB and now (figure 2)