They are using Continental 2D radars from 2014. The rest of the SDC industry uses what is called 4D high resolution imaging radars. That's why Teslas have poor performance like phantom braking under bridges.
https://arberobotics.com/product/ is one. It was rumored Tesla themselves wanted to use Arbe radars, but evidently they have ditched the plan and gone radar less. I think AutoX from China is planning to use Arbe as well.
Waymo has its own custom developed 4D imaging radar and I imagine most of the other SDC players have their own versions.