Not sure which category to place this under, but I came across something interesting while messing with my phone’s NFC capabilities and the RFID diagnostic card. My smartphone has a payment service enabled, and I’ve payed before using NFC. I placed the RFID card on the back of my phone, and it glowed red, indicating that the phone had HF capabilities. However, if I just opened a card up as if I were paying on the lock screen and signed in, the RFID card glowed green, showing that it was communicating on the 125 kHz frequency. However, all of the articles I’ve found online just talk about the NFC, which inherently uses high frequency. Anyways, just thought I should share!
For the specs:
Phone: Samsung Galaxy S20