Wh does Safari just refuse to open various webpages?

I'm on Safari 14.0.3, and it's finally stopped eating up all my RAM, but now, some websites simply won't load! I try over & over, clear the cache, try opening a different window, but still nothing, it just remains stuck. I really do want to use Safari as my main browser, but it seems if it's not one thing, it's another. And for the browser that should be smoothly integrated into all my Apple devices, it still acts like a third party attempt at a browser..