Earlier quoted context omitted.
One can examine each image and see if the object displayed in it is unique. I saw one news report which had multiple photos of the same object but taken from different angles and it must be said, from different people. Authentic very much so, however the number of images needs to be normalised with the number of objects.
There is a whole "OSINT" (open source intelligence) community doing just that and publishing counts. They also try to geolocate the images via terrain and buildings using maps, satellite images, etc to disambiguate. Pretty odd way to pass the time ... but they seem to be confident in substantial Russian losses.
* Russians leave humiliated and broken.
* Ukrainians finally capitulate.
In the first case, Russians are likely to first destroy everything in their path before leaving, because they will want to show they did not go home without inflicting more pain than they suffered.
In the second, the outcome is actually similar, but Russians don't leave for a while at least (Putin seems to intend to install a puppet government, then leave).
In both cases, there's almost nothing left standing in the whole of Ukraine. Unless they stop the fighting and negotiate, this seems to be the inevitable outcome.