TCPDF problems with the browser chrome from Mobile

Question

I'm a PHP developer, I coded an app using CodeIgniter 3 and it creats PDF files; I was using TCPDF for generating PDF docs. The TCPDF version was 6.2.25. But now I upgraded my CodeIgniter from 3 to 4.4.5, TCPDF v6.2.25 not works, then I upgraded the TCPDF to v6.6.5, It also works perfectly fine. But my problem is: when I want to generate PDF from my smart phone, it appends .html at the end of my file. ex: example01.pdf.html

Sample Code:

`
        $pdf = new \TCPDF('P', 'mm', 'A5');  // create TCPDF object with default constructor args
        $pdf->AddPage();                     // pretty self-explanatory
        $pdf->Write(1, 'Hello world');       // 1 is line height

        $pdf->Output('hello_world.pdf', 'D');`