How to Disable Web Page Checks for Focus, or Spoof Focus on Firefox Browser Tabs?

Question

Problem:
Some web sites refuse to load unless the tab is active, whereas most users appreciate tabs loading in the background. This behavior may not be specific to Firefox.

Examples:
https://www.linkedin.com/feed/
https://www.chase.com/ (especially after login)

Solution Requested:
A way to override this behavior, allowing all content to load in Background tabs. Preferred solution is Firefox-specific, OS agnostic, and works with the examples above.

Prior Research:
It's possible, but not confirmed, that the web sites may be using visibilitychange or window.onfocus or window.onblur Handle Events or Event Listener techniques, described here.
The goal of this question is to override this. Greasemonkey?

Solutions that DO NOT work:
Disable Page Visibility API Firefox Addon
Always on focus userscript
"browser.tabs.loadInBackground" preference "true"
"browser.tabs.loadDivertedInBackground" preference "true"
"browser.tabs.loadBookmarksInBackground" preference "true"
"browser.zoom.updateBackgroundTabs" preference "true"
"toolkit.lazyHiddenWindow" preference "false"

Additional Notes:
Browser successfully loads all other pages in background.

Answer 1

Disabling web page checks for focus or spoofing focus on Firefox browser tabs can be a bit technical, but here's a simplified version:

Type "about:config" in your Firefox browser's address bar and press Enter. This will take you to Firefox's advanced settings.

Accept the risk: Firefox will give you a warning about changing advanced settings. Just click on "Accept the Risk and Continue."

Search for "accessibility.blockautorefresh" using the search bar at the top. This setting determines whether web pages are allowed to automatically focus tabs.

Double-click on the "accessibility.blockautorefresh" setting to change its value to "true." This will disable automatic tab focus.