The landscape disappears after about an hour of play.

[Aero1995]

After an hour or so of play, the trees and grass disappearing.What's even more interesting is that pieces of the houses (window doors) disappearing too.

[Sui]

From what I am seeing - this is mostly related to system that started as rendering vegetation and then was expanded to render other repeated objects. That might be a repeat of:

https://git.simkol.pl/simkol/unitysim-new/-/issues/882

[Schnauzahpowahz]

I've noticed the issue on several occasions and after using several train services consecutively

Game restart seems to fix it as a temp fix.