If the size of biter expansions has increased lately, then maybe the radius of the "circle" where they settle down is ending up closer to walls than it did before. Like a bigger circle would imply a larger radius, but if the center of the biter expansion was the same distance to the walls as before ...

Basically I had to place individual wall segments to shut down biter expansion by using the "show-enemy-expansion-candidate-chunks" debug thing. It worked, it stops them from settling down too close to your wall. What happened to me might have been a fluke, but placing individual walls down around ...

Look at what happened here, and you'll get an idea of what I mean. https://www.youtube.com/live/lRDNm85FATI

6 Hours, 5 minutes, and 10 seconds. You'll see the problem. This massive nest was not native, it was the result of a biter expansion. It's enormous, which on its own would be completely fine ...