This doesn't look like a "buyer charge", just a notice from PayPal that your credit card company may charge you (independently), most likely because you are making a payment in non-USD funds?
Having said that, PayPal definitely tries to steer people away from paying with credit cards and instead paying directly through them. If you are sure it's a USD transaction then I'd brush it off as a "marketing" tactic.
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The DIN Rail Mount kit for Arduino: quickly attach your Arduino to standard DIN rail