Vegemite. The original would keep forever, even after the jar had been opened.
Some years ago the Vegemite brand was sold off. (I don't know to who or what.)
Now I notice (two instances) that Vegemite no longer lasts forever. It goes off, in a rather disgusting manner. Something changed in the formulation.
Much like the brand 'Pyrex', that used to mean high quality silica glass with near zero coefficient of thermal expansion, so Pyrex cookware could take sudden heat/cold shock without shattering.
'Pyrex' brand was sold to an Asian knock-off mob, who now make ordinary garden grade glass cookware and label it 'Pyrex.' Leading to lots of injuries when big glass pots full of very hot food, spontaneously shatter when taken out of ovens.
Or "Golden Syrup". When I was a kid, it was highly refined from sugar cane & considerably lighter than Treacle, which, in turn, was lighter than Molasses.
Now, if you buy Golden Syrup, you get what used to be Treacle, & today's Treacle is very little refined over Molasses.
OK, it may even be healthier, but it doesn't taste the same on big slabs of German Rye.
Which brings me to another point, why is it so hard to find German Rye bread, these days?
And Cassatas! There was a place in what we now call "Northbridge" in Perth, which had the most delicious Cassatas, made on the premises, but they went out of business.
Years later there was a company called Benny's who made prepackaged Cassatas, & sold them at Supermarkets,
They weren't quite as nice as the former ones, but were still pretty good.
Now, they, too, have gone, & people's eyes glaze over if you ask for such a thing.