First of all, have you ever realized how much money there is out there and how little gold?
If e.g. China invested their 2021 trade surplus into the annual gold production of every country there is, they'd still be left with 70% cash while completely cornering the gold market.
In addition, they would have to ship it to China where it needs to be stored. If they wanted to pay with it, they'd have to ship it again. It's totally impractical and unrealistic that we ever go back to a gold standard.
I mean for this exact reason, the gold standard has been dropped. There isn't enough gold and there are better ways to spend trade surplus than into physical metal.