Been desperately trying to, annoyingly, there is a whole heap of proprietary stack in the way and as much as I try to simulate it, I seem to not be able to.
I think the core of it is that the available space appears to be taking into account the entire screen, although there is a bottom tab bar.
If I manually set the height of the lazy column the issue goes away, but of course it doesn't fill the entire space it should.