TerribleTortoise

New Zealand was not Kung Fu fighting. As was foretold in prophecy.

If you want to be able to trim off the ends, I suggest a double fisherman’s instead (aka the double overhand stopper) with both strands (hold them together while you tie and treat them as a single strand).

https://www.animatedknots.com/double-overhand-stopper-knot

With either knot, after you trim, you can melt the ends of the elastic cord. It will “mushroom” a bit, which will also prevent the tips from creeping into the knot and coming loose.

A flat overhand bend in the elastic cord is what I recommend: https://www.animatedknots.com/flat-overhand-bend-knot

Justification:
Simple, not bulky, reasonably secure against shaking loose, and relatively easy to untie.

As suggested in another comment, a double figure eight could be used as well. It will be more bulky and a bit less likely to come loose.

You are correct, I had not noticed they did away with that icon until you mentioned it now.