controller of _remap seem to fail.

I build a controller: care.php in App\Controllers\wheels,
for simple testing _remap, the code is as follows.

Assuming the URL is 127.0.0.1/myproject/wheels/care/a1, it will get a1 string.
But,assuming the URL is 127.0.0.1/myproject/wheels/care/bb123, the result will appear "Method App\Controllers\wheels\Care::bb123() does not exis",
it is not as directed to the contentProcess function as I expected,
Please give me help.

PHP Code:

namespace App\Controllers\wheels;
 
use CodeIgniter\Controller;
 
class Care extends Controller {
 
    public function _remap($method, ...$params) {
        if (method_exists($this, $method)) {
            return $this->$method(); // go to a1
        }else{
             return $this->contentProcess();//go to contrntProcess
        }
    }
 
    protected function contentProcess() {
        echo 'contentProcess';
    }
 
    protected function a1() {
        echo "a1";
    }
 
}