Not a Firefox browser issue.

Hey Mr. Khalid,

  I'm happy to help to your question above. By the way, hope you are doing well

  Accessing a bank account is a pivotal step to check your checks and balances, and I understand what
  difficulty is faced by you... The problem that you might be facing may be due to: outdated Mozilla browsers
  which cause that particular browser version to not be able to access the bank's updated website (update to
  the latest version of Mozilla to get an exellent experience), and some privacy settings in your computer or
  extensions in your computer might prevent that particular website from loading (try disabling  the 
  extensions and changing the privacy settings). If none of this works, I would encourage you to reach to the  
  bank's customer support team to get this problem resolved

  Hope this post helps you..

Let me know if you need any help, Tharakram.