There are several interesting threads on Twitter about the horrible maintenance of Russian military equipment. They were showing how the tires on a lot of the vehicles were severely sun damaged. No idea how accurate this is, but the guy claimed to be retired military. He was explaining that they are supposed to rotate the vehicles so the same tires don't get continual sun exposure, and park them close together to avoid sun damage. He surmised that some of the tires were exposed to sun for years. Another thread showed Ukranian civilians rummaging through abandoned vehicles and laughing at the food rations because they expired in 2015.
https://twitter.com/user/status/1499164245250002944
Edit: sorry, this was a repeat from the previous page