When a Visual Form Builder (VFB) form has customised Fee Recovery settings and the opt-in is set to either Forced or Enable donor opt-in by default, no fees are actually charged in PayPal if the gateway, amount, or Fee Recovery settings are changed on the form.

So:

If a form's default amount is $10 and PayPal Donations is the default gateway, and Fee Recovery is pre-checked or it is forced opt-in, a donor will not actually be charged the fee recovery amount unless either the amount, gateway, or Fee Recovery opt-in is changed by the donor.

The best workaround option so far is, if you use multiple gateways, select anything but PayPal Donations as the default gateway