One Risky Solution

Firefox restart is only required when Firefox was updated to a newer version while Firefox was running. Since you run Firefox all the time, one solution is not to update Firefox.

You can set up Ubuntu to never update Firefox. Open a terminal by pressing Ctrl+Alt+T and enter:

sudo apt-mark hold firefox

This will let the update system know not to update Firefox. If Firefox is not updated it will not ask you to restart Firefox.

The Risk

One of my always open tab is a Citrix connection back to a work
server, and a restart tears down all those types of secure MFA
sessions.

This is my concern. When you run an older and unpatched version of Firefox you run the risk of throwing the security of your Citrix connection out of the window. For example, a targeted attack on your workplace may start from your computer. A hacker may be able to access your work server via your open Citrix connection.

Once you login to your workplace's Citrix web server using the multi-factor authentication, Firefox creates a "token", a random string of letters and numbers. As long as you are logged into the Citrix account the same token is used to verify your authenticity.

Since you don't usually log out, a hacker just needs to get hold of the token to get access to your workplace server.

Good Practice

• Keep your Ubuntu desktop fully updated (including Firefox)


• Do not keep the Citrix connection open when you are not actively
  working on it.


• Close Firefox after using the Citrix connection.


• Log out of your Ubuntu account at the end of the day.

Hope this helps