Is it a feature that if you destroy a nest without using a Artillery turret, the nearby nests will expand?

Yes. Any destruction provokes the growth of the base. So leaving an unfinished base is a bad idea.

This behavior was originally intended as a response to artillery fire, so that the player would not try to destroy the base with a weapon that it had resistance to. However, due to a bug, this behavior extended to any nest/worm destruction, but I liked the result. So it will remain as is

Thank you.