In the 1.21 patch you fixed this --> Aiming while prone would not take the terrain surface into account normally. This fix was for (scoped) guns and is now working great. On the other hand, and that is the bug I want to report now, is that if you have want to aim with a 'scope-device' in your hand while prone it does not take the terrain surface into account normally. And with scope-device I mean things like: binoculars, range finders, scopes in hand

So, its the exact same issue as you fixed in 1.21 with (scoped) guns. But when you use a 'scope devices' like binoculars, range finders and scope in hand this issue still needs a fix