When I try to turn off the 2.4 GHz wifi, the UI states it is off but the wifi is indeed still on. Flipping the switch in the UI does cause the 2G light to turn off for a few seconds, but it turns on again shortly after.

I downgraded to v3.211 again (and did a factory reset) and verified that on that version when I turn off the wifi and the UI shows that it is off, it is indeed off.