What you are looking for is Pale Moon (https://www.palemoon.org/ https://www.palemoon.org/) - a browser being developed with a hard fork of Mozilla Gecko render

What you are looking for is Pale Moon (https://www.palemoon.org/ https://www.palemoon.org/) - a browser being developed with a hard fork of Mozilla Gecko rendering engine without all the Firefox "shitty new, shiny things that everyone thinks is the latest fad that needs to be in the browser".