Problem & Resolve
Many users reported weird behavior when tried to connect with dApps via WalletConnect protocol on iOS 15 safari. If you tried to scan generated QR code by WalletConnect services from pc or any other sources this issue won't occurred as this works normally as expected other way to copying QR data and/or triggering connection through deeplink within safari app will not work even though you had accepted the initialize action. This error is caused by NSURLSession’s inability to process split messages normally on iOS 15, issues raised here :
In order to resolve, you can open settings page on your iOS and search for safari at the search bar, then go to Advanced->Experimental Features->Turn off NSURLSession Websocket as described at the image above.
This resolve might consider as temporary as the default NSURLSession Websocket is turned on starting from iOS 15. Following the issues, WalletConnect or Apple might resolve this in their future version