Descriptor wallet can't generate change addresses

When using the Core v22 descriptor wallet with a taproot descriptor, you can provide both an external and internal descriptor, but somehow when using sendtoaddress, it fails to add change (citing that "it can't get a legacy change address as legacy addresses are not supported in the wallet").

Together with blinding being broken and unblinded txs not being standard if they still have blinding nonces present, makes for a really painful UX for descriptor wallets.