ESD Protection for AC-coupled signals
Most differential RX circuits by their nature require that the amplifiers have CMFB (Common Mode Feedback)  indeed, differential amplifiers are mostly useless w/o this.  So the chip automatically compensates for this itself.  Some chips will have the CMFB pin available for monitoring or external capacitance but that is not strictly necessary.  Of course on startup and plug/ un-plug situation this is disturbed, which can mean that the signals hit against the ESD rails.  But the higher level protocols of re-transmit deal with this situation.

Additionally, one some advanced differential signalling situations, there is active equalization upon startup, so this packet corruption at this level is understood and handled in this case.