Bitflyer is Japan only. Is that where you’re from? I mean, you shouldn’t even see the option for Bitflyer unless you downloaded/used it from a device in Japan.
Well, it goes by your IP address and all your Locale on the device. One thing to make clear though is no matter which you need to use, you would need to provide verification that you live in a supported region. So if you’re in Japan, you can’t connect to Uphold or Gemini.
Other thing I’ll point out is that regions are limited right now. Currently nobody can link to Uphold while an issue is being sorted out (hopefully early next week).
But even then, there’s the new regional restrictions which have no timeline and may be quite a while. So if you’re not a resident of one of the 19 countries, you’d be unable to link Brave to Gemini or Uphold.
NOTICE: New region restrictions on verifying Brave Rewards with Gemini
NOTICE: New region restrictions on verifying Brave Rewards with Uphold