For the last several months, eTransfers initiated from my desktop browser (Firefox on Linux, same as you) have required confirmation via the RBC app on my iPhone. Definitely seems like they have multiple scales of trustworthiness for people/devices/activity. Kind of wish they'd be more transparent about what they are, but I guess that sort of transparency can easily become a vulnerability.
Create a separate firefox profile, all defaults, no addons, and use that only for RBC/banking.
This can easily be launched from the command line via args, when needed.
Unless you let all the tracking scripts, and auth scripts load, it thinks you're evil.
My phone app isn't verified, so it just sends an RCS message to my phone number. Works for now, but who knows what'll happen.