code: public function process(File $phpcsFile, $stackPtr)
      {
          $tokens = $phpcsFile->getTokens();
  
          $variableFunction = $phpcsFile->findNext(
              T_WHITESPACE,
              $stackPtr + 1,
              null,
              true,
              null,
              true
          );
  
          if ($variableFunction === false) {
              return;
          }
  
          $token = $tokens[$variableFunction];
          if ($token['type'] === 'T_VARIABLE') {
              $error   = 'Use of the "public" variable "%s" is forbidden';
              $varName = str_replace('$', '', $token['content']);
              $data    = [$varName];
  
              $phpcsFile->addError($error, $stackPtr, 'NotAllowed', $data);
          }
      }
docs: {@inheritdoc}