https://www.reuters.com/investigates/special-report/ukraine-crisis-russia-base
Has this Reuters article been posted here? It's an interesting read. Russian troops occupying a town of Balakliia left behind documents when they fled. Nice details there about Ukraine's counter-offensive onwards from July 19th and how Russian's weren't able to adapt.
Information like this together with the fact Russia hasn't been able to make any significant progress on any front tells us they just don't have the strenght anymore. Russian losses reported by Ukrane must be pretty close to accurate and it wouldn't surprise me if their actual losses were even higher.