Here is where I am getting my numbers from:
Tanks in 2020 - ~2,800 https://defence-blog.com/revealed-number-of-main-battle-tanks-in-russia/
Tanks lost in the conflict - ~ 800 (conservative estimate, may be much higher). https://euroweeklynews.com/2022/06/27/russian-tanks-ukraine-combat-losses/
1/4th would be ~700 tanks. So when I say that Russia has lost 1/4th of its tanks, that would be an AT LEAST 25% and may be much higher.
Great data, but my point is do not the days