The pc=ACTE part looks like an "affiliate" link -- the ACTE likely indicates that someone gets paid for your page view.

In web search results, pc=ACTE seems to be associated with Acer. Do you have an Acer computer?

Hello, and thank you for your reply. Yes I do have an Acer Nitro 5 Laptop, running the default windows 10/11 that was preinstalled. I have actually uninstalled all Acer bloatware that was unfortunately preinstalled on my computer. So I don't see how this is happening. Anyway why would "Acer" be changing the default homepage of Firefox. and How does it have the power to do so? Why does Firefox allow this to happen?

I have thought about re-installing windows 11 to a standard edition, and not use the Acer software. I am troubled by this behavior though.

There are at least three ways for other programs to create or modify files or settings to establish your Firefox home page setting:

(1) Direct change to prefs.js

When you customize settings, most of those changes are stored in a file named prefs.js which Firefox reads at startup. Since this file is well-known for the past couple of decades, other programs can inject a home page setting into this file. Obviously that's not cool.

(2) Enterprise Policy

If you open the internal about:policies page and view the Active panel, the normal content is "The Enterprise Policies service is inactive." If it has anything else, either a registry key has been created or a policies.json file has been dropped on disk to modify Firefox settings.

Normally, Enterprise Policy would prevent you from changing the setting, so this is not the most likely explanation, but it's worth checking.

(3) Autoconfig

Before Enterprise Policy was supported, a pair of script files could be used to create default values or lock values for preferences. Since this file is re-read at every startup, if your home page isn't change at every startup, this probably is not the explanation.