The three-day special military operation is now losing BTR-50s, first made in 1952 and not manufactured after 1970.
BTR-50 was replaced in service by BMP-1s.
BMP-1s was replaced by BMP-2s.
BMP-2 was supposed to be replaced by BMP-3s.
Fun fact: according to Perun, in February-April 2022, BMP-1s made up only 12% of Russian BMP-1/2/3 losses. In May-August 2023, BMP-1 share of losses went to 44%.
So with BMP-3 share being mostly stable, this shows that BMP-2s are becoming extinct, with more and more troops getting showed into BMP-1s.
And now they're down to BTR-50s that BMP-1s replaced!