"Error Opening Page" issue occur and can't open an app using a URL scheme

We are developing an app.

Our app can open the app with a URL scheme, but on iOS14.5 or later, we are having issue with the following error.

Error Opening Page

Hotspot login cannot open the page because it cannot redirect to locations starting with "URL scheme".

It did not occur on iOS 14.4. It did not occur on iOS 12 or 13.

Why does this issue occur on iOS 14.5 or later?

Can the app fix this issue? If you can fix it, please let me know how to do it.

Or is this an OS issue that the app can't fix?