Ours was a somewhat specific use case, but we were able to access all of the same props as before by switching from the cell slot to a wrapper in the renderCell method in our column definitions.

export const authorColumns: GridColDef[] = [
  {
    field: 'Actions',
    ...
    renderCell: props => (
      <CellBase {...props}>
        <ActionsCell {...props} />
      </CellBase>
    ),
    ...
  },
  ...
]