Why does the SPI slave work different between G431 and G474?

[BSout.1]

The set-up is STM32G474 master can be connected to either STM32G431 or STM32G474 through LVDS transceivers (which delays the signals). The system clock is 170 MHz on all processors. The master uses low polarity clock edge one. The 431 works at 21.25 MHz clock with low polarity clock edge one. The 474 does not work at 21.25 MHz and also requires high polarity clock to work at 10.625 MHz.

[TDK]

They should both work. Might want to measure the delay to ensure the MISO signal reaches the master in time. Hard to know the issue without seeing a scope trace or code. Ensure the slave speed is 2x or more of the master.