The problem is that these problems are not even whiteboard problems anymore. They’re often strictly timed coding exercises on Coderpad or Karat with actual mock

The problem is that these problems are not even whiteboard problems anymore. They’re often strictly timed coding exercises on Coderpad or Karat with actual mock IDEs and REPLs expecting running code under strict expectations. The more casual, flexible, subjective coding interview described by the OP is not the prevalent form of whiteboarding interviews, which has been superseded by the weeder version.