It seems to only trigger on the thread that I created. Incognito does not reproduce the same bug on the same thread, but going to a different thread I created does
Maybe you need to be the post author to get it to bug out? It doesn't do it for me using Chrome and clicking on the link in your OP, clicking another link and then clicking back.
From my testing it only happens on Chrome. It's updated to the latest version (it's not in my screenshot, but I've updated since) and it consistently gives me same bug.
Let me know if I can assist debugging this in any way.