Safari toolbar unusable since Sonoma update

Since updating to Sonoma on my 2019 MacBook Pro, the toolbar on Safari is basically non existent, the only remaining elements from it are for some reason the 'show sidebar' and 'tab group picker' buttons. Address/search bar, new tab button, refresh and anything else that was fundamental is gone. These elements do appear faintly and squashed together if I expand the window diagonally, but they are not clickable.

If I use View>Customise Toolbar, the sidebar button wobbles as if I'm in the customise mode, but nothing can be done, no options appear to add or remove elements, and when I click Customise Toolbar again, Safari crashes.

I've seen a few other people with this issue after some searching.

On the forum post linked below, someone seems to have found a solution if anyone can make sense of it. I can't seem to find the files they're talking about, and still don't understand why this has happened.

Can't Edit Safari Toolbar: Where are prefs stored now?