The whole "Russians under the mall" subplot is still painful to watch at times and I think the main reason is because there's this tonal dissonance about the whole thing that's just very... jarring.
Like s3 as a whole is much lighter and wackier than the previous two as a result of leaning into the 80s action movie pastiche, and the starcourt subplot is arguably the wackiest of them all. The Soviet soldiers are basically cartoon characters. You've got people zipping around a secret underground base in Austin Powers style golf carts. There's canisters of green goop powering a doomsday machine. The world's most precocious ten year old is Die Hard-ing through the air vents in a My Little Pony backpack. Steve and Robin spend the entire season in the most ridiculous uniforms the costume department could have come up with. Clearly none of it is meant to be taken remotely seriously.
But... the torture itself is played one hundred percent straight. The scene with Steve being interrogated by himself where he's almost crying and pleading with these soldiers as they're beating the shit out of him is genuinely an upsetting watch. (Sidenote but this is one of the few times post-s1 where I actually buy Keery as the age Steve is supposed to be because he really does feel like a terrified kid.) And even though Robin is spared the worst of the physical torture, she's seventeen years old here being slapped around and called a bitch by fully grown men. Not to mention she's still out of the loop about the upside down so she has almost no context for what's happening. Like she fully believes they're going to die.
And this part could be me reading too much into things because I doubt it's intentional but there's also this vague air of sexual threat that permeates the whole thing in a very unsettling way. There's this part where the general(?) sort of pets Steve's face/hair and he flinches away and it's just... ugh. And more generally you have two teenagers in fanservice-y outfits being menaced by middle-aged men and it all just has a very uncomfortable undertone.
And like, look. I'm not some puritan who thinks that torture and violence, even sexual violence, should never be shown on TV. But it does feel very out of place in this season where everything else is kind of a farce, and then to add insult to injury it's never followed up on in any meaningful way, and almost becomes a punchline in and of itself. Steve giving up Dustin's name is treated as another "Steve means well but he's a bit of an idiot" moment, conveniently ignoring that he was doped up with truth serum. Dustin basically says he should have just manned up about it.
(Speaking of which, Dustin straight up kills a guy and it's just - on to the next thing. I'm pretty sure at this point he's the only main character other than Hop and El to have killed another human being (unless you count Nancy and Jonathan vs. the possessed news guys) and it never gets mentioned again.)
Whenever it gets brought up in future seasons, it's largely in the context of wacky drugged up misadventures rather than "hey remember that time we were horribly tortured, wasn't that fucked up?" There's still a large portion of the fanbase that likes to insist Steve and Robin have no significant trauma because they didn't have any Vecna flashbacks in the finale.
Anyway I think if they were going to do this storyline they should have either stripped back the humour elements and actually dealt with some of the consequences of going through All That, or they should have leaned harder into the slapstick and toned down the more brutal torture aspects. But the in between approach doesn't work imo, and just makes for a frustrating, uncomfortable viewing experience.
