It is worse than that for the Russians, they are fighting this war using tactics from the 1960's and weapons that are at best from the 1970's. While the Ukrainians are using much of the same equipment, with training from the US and some off the shelf drone tech to devastating effect.
Russian MANPADs range in age from the '70s (like the 9K32 Strela-2) to 2014 (the 9K333 Verba).
Their TM-89 anti-tank mines were first publicly introduced in 1993.
Their Koalitsiya-SV self-propelled howitzer was first introduced in 2015.
Their newest Tornado MRL (multiple rocket launcher) was first unveiled in 2007 and went into service in 2014.
Their replacement of the Tochka ballistic missiles is the Iskander, which went into service on 2006.
The newest battle tank (the T-90) was first introduced in 1992, and has gone through updates three times (in 2004, 2016, and 2017).
This also isn't counting all of their electronic warfare vehicles, plus their unmanned aerial vehicles like the Orion, the Korsar, and the Orlan-10 (all put into service since 2010).
This is all just from their Ground Forces. Their Air Force has also introduced new fighter jets and rotorcraft since the beginning of the 21st century.
In summary: the assumption that any developed country (much less Russia) has no military weapons less than four decades old is likely to be wrong.