I'm playing the October Monthly game and noticed the new visible boundary for the area where we can place tiles. As I went through my game I did see the place-able area expand a few times before reaching the point I'm at now.

I'm not sure if this is the intended challenge...

Here is a video of how my game goes from 23 tiles to 0 tiles after only 5 tile placements:
https://youtu.be/DYDuJTh8OEY