SD card mystery

[PeterAit]

I just bought some new 64GB SD cards and notice that they have some extra contacts that my older cards do not (see photo). I am curious what these are for and if they have any connection with the fact that one of my SD card readers cannot read them. They work fine in the camera and can be read by the reader that is built into my laptop. Thanks.

[Telecaster]

Are the cards the SD XC variety? (It should say so on the cards.) I have some of those…they do have extra contacts and are not backwards compatible with older cameras & readers.

-Dave-