Greasy Fork is available in English.
This script allows you to get a nitro subscription code from Opera GX without having Opera GX to claim it.
Looks like your not eligible to get it or something, I read the discord article and that only happens because "the promotion is only available in certain regions."
You could read below for more information on that, the script works perfectly fine, so it's a issue on your end.
https://support.discord.com/hc/en-us/articles/19822382831767-1-Month-Discord-Nitro-for-Opera-GX-Users-2023-Promo-FAQ
Otherwise, I can't help you. Sorry
You're right, and it also requires a credit card
Yeah every time discord does a promotion it requires a credit card to get it.
It says "unknown gift" for me?