That is not how I understand it. It's not an iOS bug. It seems that older versions of the Google Cardboard SDK (probably used used by DeoVR and others) are now obsolete and not compatible with iOS14. As already stated by @N8Flight#536 (and seen on many forums), building the App with a newer version of the SDK solves the problem.
I guess it's easier said than done since the new SDK may not be 100% fully compatible with the way DeoVR currently interacts with it.