Hello Lya10,
I don't see any Bug in this, to add a "Faucetpay" on your ABP account, kindly follow this -
1) Go to https://adbuxpro.com/account/settings ,
2) In faucetpay section, you need to write down your "username" of your Faucetpay account
3) Username can be found at your Faucetpay dashboard, that's it.
your faucetpay email also works.
So, you can add your username or email.