The internet was supposed to be the promised land of open communication & egalitarian empowerment. But we've seen massive consolidation. Now, almost every site you visit is somehow using technology from Google, Amazon, or Microsoft.
This extends to the software you use to access the internet. Chrome, Safari, & Edge are obvious examples of browsers sponsored by tech giants. But even Firefox, Brave, and others rely on technology built by Google. It's putting the free & open in web in a precarious position. For example, Google is undermining Chrome extensions' ability to block ads, since that's bad for YouTube's revenue.
Building a new, open source browser from scratch is an absurd idea. The W3C spec is enormous; it'd take so much time & effort to build a compliant, perfomant browser from scratch. That's not stopping teams like the folks behind Ladybird from trying. But realistically, it'll take years for them to have anything close to comparable with modern Chrome or Firefox.
Personally, I've landed on Firefox as my browser of choice since it's at least a little less reliant on big tech while still having mainstream support. It's not the perfect answer, but at least Firefox makes efforts to protect my data & is not directly controlled by a major corporation with a profit motive.
I'd encourage you to think twice about the tools you're using. Why do you use the software you do? This doesn't just apply to browsers. Your search engine, email provider, etc are all choices that have seen massive consolidation but still harbor some better options than others.