What are the Nyquist rates of GMSL2 and GMSL3 Links?
The Nyquist rate is half the baud rate of a given signal. The baud rate is different from bit rate that it is the "number of changes in a signal per second" while bit rate is "number of bits per second". With this we can say that GMSL2 3Gbps link has a baud rate of 3GBps and GMSL2 6Gbps link has a baud rate of 6GBps since the number of bits is equal to the number of changes in NRZ.
Therefore the Nyquist rate of GMSL2 3Gbps link is 1.5Ghz (3GBps/2) while the Nyquist rate of GMSL2 6Gbps link is 3Ghz (6Gbps/2). For GMSL3 PAM4 12Gpbs operation, the bit rate is 12Gbps, but the baud rate is 6GBps (2 bits per symbol, but number of symbols or changes in signal remains the same). Therefore the Nyquist frequency of GMSL3 PAM4 12Gpbs link is 3GHz.