[Website] Can't login to NA site on Firefox

I've been having this issue for over a year now and I finally resolved it, so hopefully this will allow you to fix it on the site to prevent future issues:

On na.leagueoflegends.com I would click the login link in the top right. After inputting my credentials it would say no such combination exists. Go to the game client, logs in fine. Chrome? Fine. Edge? Fine.

I inspected the request packet being sent on login and noticed something odd, it said Region was BR1, so Brazil? But the drop-down shows North America. The exact fix to login was to click the drop-down twice to fully open it, then select North America, after that login worked fine.

This implies that while visually the option is defaulting to North America, yet somehow the associated background variable is defaulting to the 1st value on the list: BR1.

Hopefully this lets you guys fix the site and avoid future headaches!