I was trying to figure out why I couldn’t choose either of my Monzo cards that were in Google Pay as the source for one of my Google subscriptions, but my two HSBC cards that had been added to Google Pay in it’s app could.
As it turns out, that was the issue, I’d added the Monzo cards using the add to google pay button in the Monzo app. For whatever reason, this doesn’t seem to allow the card to be used with what I think is called Google Payments, i.e. use the card outside of Google Pay contactless payments.
Not a huge deal, as the work around was to delete the card and add it manually but would be nice if possible with the API.