"Play" button can still be pressed while disabled

When the play button is disabled, it can still be focused onto and pressed. I believe this wasn't the case a month ago.

1. Launch Minecraft
2. Wait for it to get to the "preparing" stage (the play button shows three dots)
3. Click on the play button
   → It shows the style of being active, then focused
4. Tab to the play button
   → It shows the style of being focused