Hi @Anonymous,
Could you please share a bit more about your issue?
Could you please share a bit more about the URL filed in your SP list?
Further, do you mean that the URL value the user enters could not be saved back to your SP list?
I have made a test on my side (use a Single line of text type column to store the URL value), and don't have the issue that you mentioned.
Please check if you have specified a proper type column to store the URL value within your SP list. You could consider create a Single line of text type column or Hyperlink type column to store the URL value.
Also please check if you have linked the URL Text Input box to the corresponding fied in your SP list. In other words, please check if the Update property of the URL field Data card which contains the URL Text box is set to following:
URLTextInput.Text
If the issue still exists, please consider take a try to re-create a new app based on your SP list, then check if the issue is solved.
Best regards,
Kris