safari websites reloading?

Don't think there is an Apple Support document specifically for it. If anything, I'd start with basic HTML web page and Javascript coding, which isn't all that difficult. Using the web inspector is actually fairly intuitive, but you will quickly find out the most complex and resource-demanding page elements are those designed to grab your attention: interest-based, targeted advertisements and tracking. That's how programmers get paid. Unfortunately the more attention-grabbing, the more they are prone to errors. It's a dysfunctional system.

It's been my experience the cause is a poorly coded advertisement. So-called "news" sites are by far the worst offenders.

It would require some patient troubleshooting on your part, but sometimes the recalcitrant page element(s) can be identified using the Safari's Develop menu's Web Inspector console. Not that you can do anything about it though.

Your definition of "reputable" differs from mine 😄

I can't really describe how to use the Web Inspector, but it's not really intended for anyone other than the website's developer — and they're almost always clueless. They often claim total ignorance when it comes to advertisements, even though they're the ones ultimately responsible for the material they host.

In most cases the problem goes away when the guilty parties eventually change their page code.

You could try content blockers but I don't use any and don't have anything in particular to recommend. Even if you do, content blockers themselves can cause the very problem you're experiencing.

By the way the "webpage was reloaded" status message is an improvement over previous Safari versions, which would terminate the entire page given a common error such as self-referencing page element. Now, Safari terminates only the problematic element while loading the rest of the page so you're not just looking at a grey screen (which itself was an improvement over having the page reload endlessly). As such it lets you know the page was reloaded, but you might be interested in knowing not all elements were reloaded. Identifying the specific element is where the Develop menu can be useful.

You're welcome jeffreythefrog. You might find the problem will resolve itself, when the problematic page element (advertisement, probably) eventually gets replaced with something else.