Just FYI - I just did my first transfer of funds from Itch to Paypal (they hold the funds for a minimum of 7 days, then you can transfer it to Paypal if you have at least $5 waiting). It turns out that when you do this, they actually give you way more information... and that information doesn't line up with the limited information they give you until that point.
Before I did the transfer, it said I was getting ~60% of what had been paid. On the transfer details screen, that went up to ~80%. I have no idea why these two values are so different, or if/how you can see the accurate value before doing a transfer. But it gets there in the end...