Unfortunately, there's no way to change the order of the built-in Other Bookmarks list on the Bookmarks Menu. However, you can create a new "smart folder" that lists the contents of Other Bookmarks in reverse chronological order. This uses the magic of places queries, the code behind other blue "magnifying glass" folders you may have discovered on your Bookmarks Menu or Bookmarks Toolbar.

You can try the "bookmark" here: https://www.jeffersonscher.com/res/sumoplaces.html#OtherNewest

(There isn't a way to remove or move the built-in Other Bookmarks item from the menu and replace it with this. An add-on or custom style rule could be used to hide that built-in items if you really need to reclaim the space.)

Thanks for letting me know that there is no fix, just a work around. Sorry to hear, though, that Firefox doesn't comprehend the logic of having the most recently created other bookmark appear at the top of the list and doesn't care to fix or allow the user to fix this.

Why do you think making a suggestion wouldn't be considered for a future update? You can suggest feature changes here (it's where "Submit Feedback" on the Help menu leads):

https://input.mozilla.org/feedback/firefox

Your first reply was helpful and I made a suggestion after I got it. IMHO it seems intuitive that the order should be last bookmarked at the top of the other bookmarks list so it's a little disappointing to see the opposite order. And large organizations often have a circular file cabinet under the suggestions bin, but I hope that Firefox surprises us.