It’s not a matter of “which figures you want to believe.” Even your own source made clear that Ukraine deliberately lies. “Initially, the known number of Ukrainian military casualties varied widely due to the Ukrainian Army drastically understating its casualties,[17] as reported by medics, activists and soldiers on the ground, as well as at least one lawmaker.[17][18][19][20][21] Several medical officials reported they were overstretched due to the drastic number of casualties.” “Mid-June, Davyd Arakhamia, Ukraine’s chief negotiator with Russia, told Axios that between 200 and 500 Ukrainian soldiers were killed every day.”
Russian defense minister Shoigu has said that Ukrainians were losing 2,500 a week...so 10,000 deaths a month. He also stated when he outlined the move out of Kherson city that in October alone 13,000 Ukrainians were killed. And during the announcement of the partial mobilization two months ago Shoigu said that there were already 61,000 Ukrainians killed in action and 50,000 wounded.
And even if one wants to believe the 17,000 figure from the BBC in your source for Russian deaths which they admit they have added 40-60% guestimate to the 8,000 they found in order to cover deaths that they may not have names for there is no comparison to the massive Ukrainian deaths.
Here’s a little clue for deciding what to “believe.” Ukraine has mobilized 7 times in this conflict. Until September Russia had never mobilized (and most of the new mobilized troops are still in training; not in Ukraine.)
Russia entered the war with under 200,000 troops...how much “under” has never been disclosed. But, since they currently have 150,000 without having had a mobilization obviously the KIA plus wounded (which means wounded enough that they can’t return to battle) they have not incurred “massive” deaths.
No one ever expected a war of Russia vs. NATO “was estimated to be a quick operation.” Actually many analysts believe that the Russia vs. NATO war may go on for years.
The war between Russia and Ukraine WAS quick, basically over around June. What is going on now is a new war between Russia and some sort of a hodgepodge force, some leftover hohos and an amalgam of mercs from various places including ISIS and Al Quaida fighters +Poles and other nato troops stupid enough to want to be involved. But the hoho army that began the war early on no longer exists, neither men nor equipment...