You can read the Wikipedia article on them here.
Something to remember about obsolete tanks is they're really only "bad" if the enemy is completely up to date.
Even so, a "recently" obsolete tank might still put up a decent fight against a top of the line tank.
It should be noted that the M4 Sherman was able to win against nominally superior tanks in WW2, and the same holds true today if you were using smart tactics and hitting where the armor is thinner.
Something the Russians and Ukrainians have against each other is knowing exactly how thick the armor is and where it's thinnest of each other's designs because they are, for the most part, using the same tanks.
But tank-v-tank isn't really what a T-62M is for nowadays.
Tanks are wonderful armored bunkers with a machine gun which is protected against most everything being tossed around an infantry battle.
If they employed intelligently, then they will be in mutual support with infantry.
The 115mm gun on the T-62 is adequate for any infantry support role, and is only found wanting against more modern tank armor.
The engine is generally regarded as reliable and while not fast it's mobile enough.
It's perfect for conditions where "we need A tank" perhaps even "we need a GOOD tank" but not for "we need a MODERN tank", though the T-62M has a lot of modernizations on it.
Not least of which is an ATGM fired through the main gun.
It might even do better against top attack missiles because it's ammo isn't directly under the turret ring where those missiles tend to hit most often. Though "better" might be a technical term for "everyone in the turret is dead, but at least it didn't catch fire!"
Or it could be a desperation move by the Russians as everything is running out and all their men are dying in the triumphant victory of the Ukrainian Nazi Warlord Master Race (©2022 The Abode of McThag, all rights reserved, you heard it here first, no take-backs).
It's probably not a desperation move. It's probably simple attrition and the T-62M is available in numbers and adequate.