I've been daily driving Firefox since 3 years ago, the only time it doesn't load a site properly is when I lost internet connection mid-loading. Some people keep saying some sites don't work with FF and yet none of them was able to give a single example.

I’m a die-hard Firefox user (in part because I’m a web developer and prefer the dev tools). But I have seen a couple of sites that only work with Chromium-based browsers. Both are owned by Microsoft, though, so I assume they’re breaking things on purpose to push Edge or something. There’s no significant features Firefox is missing. (Safari is the problem child for web developers now. They tend to be last to support new CSS/JS features.)

I've had some "Apply to Job" buttons on job sites not display in Firefox but show up fine in Chrome/Safari.

Maybe it's because I use sidebery but Firefox is very Laggy for me in comparison to chrome, I use it Firefox because I don't like google's practices, and I like my sidebar, but I do miss the speed of chrome when you have several tabs open

However, my problems may also be due to windows, I've been having issues with my pc and I Def need an OS wipe

Same here, only I use a few different browsers between work and home. I've never once had to skip over to a different browser because Firefox couldn't do it. Only thing that ever stops a website from working for me is uBlock Origin, and that just means it's usually doing its job.