Just updated to Ventura 13.7.4 & lots of bugs...

Saxman wrote:

Well, at one point I did get rid of all third party "junk" I had on my iMac, yet didn't find the OS working any better than before, and reinstalled this one app, just to enable it to function better. However, after a lengthy session on the phone with support, and letting them see all the buggy behaviors (that even they couldn't explain), it was suggested I reinstall my OS, which I will do, clearing everything, and starting fresh with a fresh OS.

Uninstalling the junk may not actually fix anything if the junk made any system modifications. Some people get lucky and uninstalling the junk software will fix their problems, but for others people must start over from scratch.

When you performed a clean install of macOS, did you first erase the disk followed by reinstalling macOS? Then, did you test Safari with those websites before installing any third party software and before restoring from a backup? If not, then you most likely brought the problem back onto the clean install.

FYI, after performing a clean install and you want to get rid of junk, then when you restore from your backup.....make sure to only transfer your home user folder and making sure to deselect Settings (both system & local account) and Applications. Even this may still bring back something unexpected, but it may be a good compromise so you don't have to manually restore just your data files.

Of course I'm also assuming you don't have any odd or complex network configurations that may be interfering. I don't recall when Apple introduced some of the newer privacy & security features into macOS regarding hiding one's IP address, etc., but those have been known to cause problems. Plus browser extensions & plugins are another source of browser issues.

I agree with @dialabrain, third party software is most likely to be the cause of the problem. Many people discover the problem when they upgrade their OS. I have not had any issues with Ventura, nor has my organization...even with the more troubling macOS upgrades of Sonoma & Sequoia. macOS needs no anti-virus software, cleaning/optimizer apps, or third party security software. These types of apps usually cause more problems than they solve because they interfere with the normal operation of the OS at a low level, plus they all weaken the security of macOS to a greater or lesser extent. I think everyone should read the following article as it will keep their devices running smoothly while also protecting their devices & themselves:

Effective defenses against malware and other threats - Apple Community

Don't know what sites aren't working in Safari for you but feel free to send a bug report from the feedback page.

Feedback - macOS - Apple

Just to add, we still have a 2017 iMac running Ventura 13.7.4 and Safari 18.3 seems to work with any sites we visit.

Saxman wrote:

Why do they keep demonizing all third party helpers, if Apple's own OS fails to keep our devices working well?

If I was a betting man I would bet the reason your Macs don't work well is because the third-party junk you install. So you need one piece of junk to fix the problems caused by the others. Fortunately, our Macs work well because we don't install junk.

+1 - updated from 13.7.2 to 13.7.4 and audio processing for certain VST3 plugins got broken (known as the double sample rate bug, this happened before with macos updates).

I can't see why a security update should affect audio processing on my professionally used mac. It just makes no sense at all.

[Edited by Moderator]

By the way the same (reintroduced) audio bug was reported for latest security updates 
for Sonoma and Sequioa as well.

So this affects all professional users of the latest 3 major Apple macos versions

Just to add, I never heard of the 32degrees.com site before you mentioned it but It works perfectly fine with Safari for me.

Some people just can't be helped.

Saxman wrote:

Not by snarkiness, that's for sure.

True.