I've fully refunded an order (payment via PayPal) and customer said I'm missing a few bucks.

I’ve refunded every single dime, but customer reached out and mentioned I still owed her 6 euros (payment via PayPal)? Please see attached for proof on my end. I don’t know if it’s the PayPal fees or whatever. I just want to get to the bottom of this. If this indeed is not my fault, please help me explain to the customer that I’ve already fully-refunded her and why this is happening (i.e. she’s missing a few euros). Thanks so much!

Shopify screenshot:
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PayPal screenshot: