The difference is normal
The plan price is set in US dollars. The amount billed on the payment provider's page can be slightly different, because it includes payment provider fees, service fees and network (gas) fees. The difference is usually about 1% to 3%.
When to stop
If the difference is more than 5%, do not proceed with the payment. Contact [email protected] instead. If you pay anyway with a difference above 5%, you do so entirely at your own responsibility (Terms of Service, Section 7.5).
What the difference is not
This fee difference is not an overpayment and is not refunded. Overpayments, meaning sending more than the Invoice asks for, are handled separately; see "Underpayments, overpayments and duplicate payments".
Exchange rate
The provider converts the USD price into the coin you choose and locks that rate only for a limited time on the payment page. After that, the amount of crypto due may change, so pay while the rate is still locked.

