That seems reasonable to me. I assume they are using stripe for payments, so that's already 2.9% gone to facilitate you giving money to the project.
Sponsors have a slider that allows them to adjust their tip from 5% to 100% of their monthly donation. We figured minimum 5% would cover our compute & merchant fees but left it to the community to decide what we should get. We thought this was the most aligned approach with open source. Totally open to other ideas and suggestions though.
So no, if you're taking a minimum of 5%, then any reasonable person is going to assume that you've already deducted the processing fees, not covering them out of that 5%.
I don't think you're being open and honest here.
The text may be imprecise, but it's a long way from dishonesty. In my opinion dishonesty requires a motive, and I don't see it here. If the 5% did not include fees, it would perhaps be different.
In a perfect world, Stripe and the credit card companies could waive the fees for donations, but that is not the case.
Someone has to actually cover those fees.
I agree it is not simple, but it proves it is doable.