Hi Mike, I haven't seen that one yet.

Do you use any security software that intercepts and filters your browsing? That could include Avast/AVG, Bitdefender, ESET, Kaspersky, and probably others.

Maybe try disabling http3, a newer protocol that some sites use. Here's how to test that:

(1) In a new tab, type or paste about:config in the address bar and press Enter/Return. Click the button accepting the risk.

More info on about:config: Configuration Editor for Firefox. The moderators would like us to remind you that changes made through this back door aren't fully supported and aren't guaranteed to continue working in the future.

(2) In the search box in the page, type or paste network.http.http3.enable and pause while the list is filtered

(3) Double-click the preference (or click the toggle button at the right end of its row) to switch the value from true to false

Then reload the page or try again in a new tab. Any difference?

Try changing DNS over HTTPS (DoH) to "Off" or "Max Protection" and in Connection Settings change "Use system proxy settings" to "No proxy".

Does it still happen in Troubleshoot Mode?