Gross revenue is what your game has sold, not the current available money you have in Itch.
If you have already requested a payment, then it is normal that the money available to withdraw is less.
If you have never requested a payment, the default system always shows a 30% tax (it is a reference value, not the true one), this value is only updated at the time you request your payment.
The 1.30 that you have pending is because that payment was made very recently. There is a delay between you sell something and that money is available to you, as there may be problems with the transaction or the buyer may request a refund.
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