Good news for the brave ones, that might afraid that Firefox 115, this is the last piece of software, that you can browse the web.
Pale Moon project from Sweden:Pale Moon is an
Open Source, Goanna-based web browser available for various operating systems including Microsoft Windows, Mac OS and Linux (with contributed other operating system support), focusing on efficiency and customization.
https://www.palemoon.org/------------------------------------------------------------------
Feel free to explore by your self, this browser.
Pale Moon has the graphical interface of older Firefox.
Under the hood, there is Open source along Firefox plug-in.
I am now willing to test it, and see if this is usable as I need it to be.

In the end of the day,
when mainstream solutions closing their doors to you, then your only solution is the discovery of available Open source solutions.
Pale Moon forum = browser support questions.
https://forum.palemoon.org/index.phpI think that all of us using Firefox for over 15 years, we can easily adapt to the older Firefox graphic interface.
Regarding security concerns, Pale Moon project this is
European based.
Latest...
palemoon-33.7.1.win64.installer.exe this has the size of 35MB
I will recommend, making first a system restore point.
Then you are free to safely explore this browser.