Transaction Declined: Invalid Payment Method. [Or-Ccseh-05]

Is you google account is activated..

Please activate it if not and within a day, you're good to go.

Google Account verification link

i've contacted google regarding this case, as i've been facing similar one and upon it's inspection i've received the following reply:

Upon checking, I understand that you're unable to add testing cards.
I would like to inform you that testing cards can't be added to Google Payment profile as payment Method.

Thanks!

Upon further investigation by payment service prividers i've been assured: For a bit of context on how Google Pay works to test payments. When you’re using your test mode API keys, the actual details of the card are ignored, and they get replaced with the PSP 4242 test card. To test authentication you will not be able to add the test cards to your Google Pay account however there is a work around for this, you add our 3DS test cards to Chrome and use the PaymentRequest button with them (making sure to choose them, and not Google Pay itself). Unfortunately there is no direct method to testing this in your the app.