From v4.5 to v4.6
SPI Byte/Bit ordering
SPISettings class has been revised to be consistent with Arduino ESP8266, ESP32, RP2040, etc.
which provide a bitOrder setting but not
Bytes are now always sent LSB first, which corresponds with the system endianness. Bit order simply indicates how the bits within each byte are sent on the wire. This is predominantly MSB first, the default.
SPISoft class has been upgraded to support bit ordering, transactions
and includes automatic delay calculation for the ESP8266.
See Issue #1428.