That's the engine radiator cover - the engine is probably overheating so it's common to see them driving with the covers open to get better cooling.
A (probably) unintended benefit is that the open engine deck plating also becomes a de-facto RPG screen for the turret's rear arc (4 o'clock to 8 o'clock) with the drawback that the turret can't traverse through that arc.
Note that the sunshade over the pergola also works as a drone-delivered anti-hand-grenade screen (since we've seen several Russian tanks immolated by UA drones delivering frag or whatever grenades.
Note that the T62 is the last Soviet tank with a four-man crew and no autoloader (so it's got that going for it).
With our tanks, you can fire the main gun from the TC's station (known as 'degraded mode' when you only have a three man crew).
I don't remember digging deep enough into Soviet manuals to see if that was one of their capabilities as well, but it would seem to actually be desirable for T62 operators in 2022; shortages of trained personnel, ease of training a Gopnik to stick big pointy end of shell in first, range estimation for the 115mm not being a high requirement, high probability of having to bail out of a stricken tank, etc.