I want to search all the subfolder files and make them into files, but the print and append values are different.

import os
from tkinter import filedialog
from tkinter import *

files = list()

class FileList:

    def FolderOpen(self):
        window = Tk().withdraw()
        dirName=filedialog.askdirectory(initialdir="/",title='Please select a directory to check.')
        return dirName

    def FileSave(self):
        window = Tk().withdraw()
        title = 'Save File'
        ftypes = [('txt FIle', '.txt'), ('All files', '*')]
        filename = filedialog.asksaveasfilename(filetypes=ftypes, title=title, initialfile='FileSearch.txt')
        return filename

    def search(self, dirname):
        #files = list()
        try:
            filenames = os.listdir(dirname)
            for filename in filenames:
                full_filename = os.path.join(dirname, filename)
                if os.path.isdir(full_filename):
                    self.search(full_filename)
                else:
                    print(full_filename)
                    files.append(full_filename)
            return files
        except PermissionError:
            pass


File = FileList()
FolderFind = File.FolderOpen()
filename = File.FileSave()
file = File.search(FolderFind)
print(file)