What is the maximum speed rating of the SDXC slot reader on the MacBook Pro M4?

Based on what I have gathered, the SDXC card slot on the MacBook Pro M4 supports UHS-II cards, offering a theoretical maximum transfer speed of up to 312 MB/s.However, Apple has specified that the actual maximum data transfer rate achievable through this slot is up to 250 MB/s when using UHS-II cards. For UHS-I cards, the maximum speed is up to 90 MB/s

 The  for the internal  reader  is 250 MB/s for a UHS-II card and 90 MB/s for a UHS-I card For as far as I know