Payment processor fees are typically something like $0.30 + 3%. So if your game only costs a dollar, you're going to lose like 33% from that. Plus whatever your Itch cut was set to, and the fee to transfer to your destination PayPal account. It can add up. If your game is like $15 though, $0.30 per transaction is a much smaller percentage of your total earnings. So consider raising your price. It won't just cover the difference, it will actually lower the percentage that you lose to fees because you'll have more income across fewer transactions.
I have a game that's $6.99, with my Itch cut set to 10%, and about 83% of gross revenue ends up in my PayPal. I think Steam and Google Play take like 30% so that seems pretty good.
Oh, another thing that might affect it is your tax situation. If you're outside the U.S. Itch might have to withhold some of your money for the IRS. It depends which country you're in and if you filled in the tax interview correctly.