ESP32 Minimum SPI Speed?

[Talesduque]

Hello, I've ran into some problems while trying to communicate to a FPGA via SPI. After troubleshooting tons of different stuff I went on the internet to research about the SPI frequencies, only found info about highest speed and the rule of the frequency being a number that can be obtained when dividing 80MHz by an integer.

The problem is: Im sending a constant value ('33') from the FPGA to the ESP32 via SPI. When using the Logic Analyzer, I get to see the values going through, and sometimes the value that shows of a transmission is random, sometimes its 66 (which is shifting one bit to the left), etc.

Does anyone know what is an optimal speed? (ESP WROOM32)

The FPGA is running on a 25Mhz clock, my SPI speed currently is 5MHz.

Thanks!