Hmmmmmm....
Somewhere I think I saw that number, but it was reported as Russia's claims for the number of Ukrainian battlefield losses!
I thought at the time: it's odd that Russians would claim the same number of Ukrainian losses as Ukrainians say for Russian losses!
I'd assume the word "irretrievable" refers to all deaths, seriously wounded and missing or captured.
its a press release from Moscow. From March. The number is higher now, I would assume.
Note: the 434k not only includes the dead, but those too badly wounded or otherwise unable to return to the Front.
Moscow claims what it wants, and has a big incentive to keep Russian loss numbers on par with their UKR claimed losses.