If you take the train in the Netherlands and want to walk through the gates with a QR code on the screen of your smartphone, it may happen that your bonsai Mastercard is detected if your NFC is still turned on at that time. You will then be charged the amount of your journey (or 20 euros if NLOV no longer detects you when you check out).
To request a refund, you can contact the NS-OV helpdesk. You fill in a list here and they will refund you this amount if you can prove that you had a valid ticket for the journey.