There's a lot of fumbling in the dark about T-62s here.
T-62 entered service long before 1980. It's a further development of the T-55.
Soviets liked the idea of the T-62, which was a somewhat enlarged T-55 with a revolutionary new 115mm smoothbore gun. Similarity to T-55 significantly eased retraining and logistics.
However, it was only a match for the early M-60s, and would be outcompeted by later developments. T-64/72 was the longer-term solution for Soviet armoured forces.
Many Soviet client states didn't buy the T-62, because they didn't think that it offered enough of an advantage over the T-55 despite costing more. So it was mainly USSR and some countries like Cuba that fielded them. DPRK developed much of its tank force from T-62, didn't it?
T-62 was a solid and reliable tank, I think Israel even rebuilt some because they are useful and they work.
There was a significant modernization program for the T-62, forming the T-62M. Later models of T-62 had laser rangefinders, which would have been a useful addition during the Cold War.
Tanks like T-55 and T-62 are not what you want in fighting against MBT in Ukraine today, but there continues to be a need for a protected, mobile gun system. I mean, the U.S. is going to spend millions per-tank for a 105 mm light tank, so T-62 doesn't look so bad.
T-62 is not so oddball in the Russian army today. They are supplying allied T-62s in Syria. T-62 is a development of T-55, which Russia is also supplying in Syria. If you can maintain a T-55, you can maintain a T-62.
Reportedly, T-62s are relatively survivable. They don't combust as much as the non-upgraded autoloader tanks like T-72A or T-64. They can take hits from RPG-7. This gives them a valuable fire-support role.