its because you are measuring stable Gold in volatile fiat which is being printed every day depending on the factors you mentioned (interest rates, expectations of future growth, sentiment etc).

because you are getting paycheck in fiat, you are psychologically programmed to think of fiat as something stable, and Gold as volatile.

while in reality prices expressed in Gold ounces remained fairly stable for example: https://i.redd.it/1b5mfrqkxxef1.jpeg

You're wrong; the prices of precious metals have never been stable, which is why bimetallic systems have always had a lot of problems papering over the notionally fixed exchange rate between coins of different metals.

That said, I agree that e.g. gold under a regime where most things for sale are priced in gold is more stable than gold as a novelty investment under a fiat currency regime.

When things are priced in gold, most of the demand for gold comes from the fact that it's useful as currency. All of the phenomena we have now still exist, and they disturb the price, but they're small effects compared to the demand for currency.

In the fiat regime, that source of demand is gone. All of the same random effects still push the price of gold around, but because the price is so much lower (due to much lower demand), the price swings are wilder.