I'm experimenting withi my Rampant experience and I noticed that nests are getting a health bonus based on evolution percentage. This seems to be working strangely, as each nest seems to have identical health values regardless of level. Compare this to worms, where a level 5 worm may have twice as much health as a level 1 worm. Is this by design? It seems to me that if evolution is supposed to have an impact on spawner health there should still be some base improvements by virtue of being a higher level hive.

This is the mechanics of Factorio 2.0. Even standard nests increase health with greater evolution
In Factorio 1, Rampant nests of different levels had different health. Now it will differ only if the "final enemy level" setting is different from the default. However, nests of different levels differ in resistance and biter production rate

Evolution doesn't affect the health of worms, so worms remains as it was. So yes, that's how it was intended.