This has actually always been a problem - It was just much harder to trigger in the old interface. It was also much harder to trigger when the loading animation was still there, because the loading animation would push the rest of the page down, making it hard to click the "Make Your Turn" button again while the turn was loading. So preselection combined with removing the loading animation explains why more people are running into this now despite it having been a problem for ages.

I don't consider it a priority to fix, because you can avoid it by simply not clicking the button until it's done loading. The button will appear "grayed out" when the turn is loading, so just don't click it until you see that it's no longer grayed out.

The "Game Over" buttons not working on page reload glitch is also something that's been around for a long time. I'm not looking at fixing it at the moment. The battle is ended properly despite the end page failing to load, so don't worry about the battle not counting, or losing out on your loot!

Fixed in today's update!