It also depends on how they pay. Paypal and Credit Card fees are different. On top of that, if a person is subscribed to many creators, their fees get split (I believe this is just with credit card payments but i could be wrong) as they lump sum the charge so that creators split the fees between them instead of charging the person for each individual subscription and charging the artists full price on fees.
As for the % and any differences between lower and higher pledges, i think mostly what they mean by that is lower pledges, there is less to go around so it probably seems like you are getting less when you have small pledges. (Especially if they are paying by credit card because there is a larger flat rate charge for credit cards.
SO For example (based on https://patreon.zendesk.com/hc/en-us/articles/204606125-How-do-you-calculate-fees-)
A $1 pledge gets the following treatment (approx) if using a credit card (assuming you are the only person they are subscribed to)
5% to patreon = $0.05
1.9% + 30 cents per transaction = $0.02 + 30 cents
Paypal transfer = $0.25 (min)
This leaves you with ~$0.38 of that $1. (Which is 38% of your earnings, left for you)
A $100 pledge gets the following treatment (approx) if using a credit card (assuming you are the only person they are subscribed to) (If you are making a couple hundred dollars, you should look into using payoneer, it’s cheaper for payout fees since its a flat $3)
5% to patreon = $5
1.9% + 30 cents per transaction = $1.90 + 30 cents
Paypal transfer = $1
This leaves you with ~$91.8 (which is 91% of your earnings, left for you)
Hopefully that makes sense.
Lots of people alternate their pledges to different people every month. They subscribe to more or less and some people change their payment methods, etc. So your fees will always change.
The fee’s really aren’t that bad considering how much work and management goes into patreon. How they handle a lot of things you don’t end up having to handle because of their service. It has always been worth it imo to pay for this service (and the services that go into it.) I know it can be hard if you aren’t making a lot yet but in the end its usually worth it.