And since you won't be able to modify web pages, it will also mean the end of customization, either for looks (ie. DarkReader, Stylus), conveniance (ie. Tampermonkey) or accessibility.
I use Firefox and LibreWolf trying to avoid Chrome based browsers, but doesn’t Mozilla get the majority of the funding for Firefox development from making Google default search? I’ve purchased a few of Firefox’s paid features, VPN, etc hoping that it would contribute to getting them a new business model.
You're doing a great job and if more did what you did, they wouldn't have to rely on search revenues. They know most users switch search engines. Those defaults are what fund browser development. Firefox are not in the search engine market, and if they took that sacrifice, they'd go bust and wouldn't be in the browser market either. It sucks, and it isn't glamorous, but it is the only way they can financially compete in the browser market at all. Browsers are complex and millions of lines of code and only getting more complex. It is far from cheap.