The new Payjoin spec is not guaranteed to work with BIP79 so I would remove its BIP21 key as a signal for payjoin.
MODIFY
WalletWasabi.Gui/Controls/WalletExplorer/SendTabViewModel.cs
WalletWasabi.Gui/Controls/WalletExplorer/SendTabViewModel.cs
@@ -101,7 +101,7 @@ namespace WalletWasabi.Gui.Controls.WalletExplorer
{
base.OnAddressPaste(url);
- if (url.UnknowParameters.TryGetValue("bpu", out var endPoint) || url.UnknowParameters.TryGetValue("pj", out endPoint))
+ if (url.UnknowParameters.TryGetValue("pj", out var endPoint))
{
if (!Wallet.KeyManager.IsWatchOnly)
{

The new Payjoin spec is not guaranteed to work with BIP79 so I would remove its BIP21 key as a signal for payjoin.