Okay, let's break this down once and for all.
What were Loki's "crimes"?
1) Snuck a small band of Jotuns into the vaults of Asgard as a prank, knowing full well that they would be stopped before they could do any real damage. His reasoning? Thor was brash, arrogant, reckless, and violent. Loki wanted to delay his unstable, genocidal brother taking power and leading Asgard into ruin. This is all fully established in the movie. He got those Jotuns killed, I'll give you that one (or would, if any of you even fucking cared about them). But from his (and any other Asgardians') perspective, not knowing they were his own people, having been raised for 1500 years in a racist society that viewed Jotuns as lesser and unworthy of humane treatment? Hardly a loss, especially in the service of protecting his home.
2) Being handed regency of the throne until Odin recovers, due to Thor's banishment. Loki never stole it, never wanted it, was stunned to be given it. As the other Prince of Asgard and the last remaining link in the chain of succession, there was absolutely nothing wrong with this move, on the advisors' part for handing him the power, or on Loki's part for claiming it.
3) Refusing to undermine Odin's authority while he's incapacitated. His own motives here are completely inconsequential. Loki is right not to immediately contradict the King the moment the crown changes heads.
4) Trying to kill Thor and his friends, destroying a small New Mexico town. I'll give you guys this one (though again... no one seems to mention it. Huh.)
5) That whole Kill Odin/Kill Laufey switcheroo. Here is where the difference between explaining and excusing becomes very important. Loki, having just learned that he's adopted and is the son of Odin's sworn enemy, is having a bit of an identity crisis and is desperate for some indication from the only father he's ever known that he's worthy of love and respect. Having been raised on racism and casual genocide, it makes sense that his idea to win Odin's love and prove his loyalty to Asgard is to eliminate that enemy. This does not excuse Loki's actions; I've never heard/read a Loki fan attempting to excuse his actual wrongdoings. But it's not difficult to understand what motivated him.
6) Trying to destroy Jotunheim with the Bifrost. This is really more of a 5.5 lol. Kind of more of the same shit - desperate to prove himself, lots of twisted, psychotic messages in his upbringing. Again, not excusing his actions, here. There is no excuse for attempted genocide.
Funny how all these arguments that Loki is evil and always has been center around the first three points, where he wasn't actually wrong, and rarely if ever bring up the last three, where he was clearly misguided at best.
Avengers (2012) ...lordy. Here's a doozy. Let's start with this, shall we?
"Marvel confirms Loki was mind-controlled in The Avengers."
To anyone who actually watched Thor 1, this should have been obvious. Why? Because he's trying to fucking rule Earth. Loki. Never. Wanted. A. Throne.
If that's not enough, and Marvel directly confirming this isn't enough, look at the evidence: sickly blue light from the scepter in his eyes, same as Clint and Selveig when they were controlled. He's pale and sickly looking, clearly unwell. He can't stand or walk on his own and is clearly in pain. He was tortured.
Yes, sure, this is absolutely a willing accomplice meeting with his buddy. Not at all a traumatized victim still under the thumb of his abusers and being forced to do their bidding. Don't all friends and allies threaten each other with unimaginable pain? 🙄
1) "He killed 80 people in 3 days!" Thanos shoving him through the Tesseract caused a power surge that obliterated the structural integrity of SHIELD headquarters and caused the building to collapse. That's it. That's the body count y'all can't fucking shut up about and keep mindlessly quoting Natasha, who spun the events to sway Thor to their side. Loki didn't kill 80 people. A building's inability to handle Loki traveling killed 80 people.
2) *chirp... chirp...* 🦗🦗 Y'all need some help? I never hear about anything else from this movie. Shall we just move on?
Oh, wait. There's one more...
2) "He stabbed Thor!" Yep. Finally free of the Mind Stone's control, Loki looks out over the destruction he helped cause, has a little freakout because he's not evil... and then stabs Thor to get free and a little bit to save face because he does have an ego. What's more damaging to it in the end - admitting he was someone else's puppet this whole time, or playing into Thor's bias that he will always betray him because that's just what he does? Also, he stabbed Thor with the tiniest blade in the history of blades. Like, there was no way that thing was ever going to hit anything vital. Thor was in no danger there. It hurt, I'm sure, but he's had worse. Loki did it to get away, not to harm him.
Thor: The Dark World (2013)
1) Still freshly liberated from Thanos' control, Loki is snarky and dismissive as he faces Odin, because he already knows nothing will sway the stubborn old bastard. His mind's made up and Loki has far too much pride to grovel, or to even admit the shit on Earth was never his plan. Oh, no. The God of Mischief is snarky! The horror!
2) Gives the bad guy directions. Not very good ones, at that. Every time I watched this movie, this moment came across as Loki just telling the Kursed how to slip past the guards swarming to round up the other escaped prisoners. Kursed went straight to the shield generator thingy and smashed it to pieces. Not straight to Frigga. Mobius and the shitty Loki series writer can retcon this all they want, but Loki did not murder Frigga. Loki did not lead the enemy to Frigga. He wasn't trying to lead him fucking ANYWHERE.
He was extremely helpful through the rest of this movie, right up until his "death." He was still chaotic and delightfully sarcastic and holy fuck I love this movie... Anyway, Loki was pretty much firmly on the Good Guy team in TDW. But I'll address it anyway...
3) Faking his death and pretending to be a guard to trick Odin, and then pretending to be Odin to trick Thor and the rest of Asgard. ooooo so evil! He sat in a chair and smirked. Someone call the cops! He didn't even hurt Odin!
In Thor: Ragnarok Loki saved the day. Twice. In Infinity War, he died a very stupid, avoidable death trying to save the day, or at least save his brother.
What, exactly, has he done that was so wrong as to paint him as evil and deserving of continued abuse and degradation? Find me one Avenger who hasn't done more damage than Loki ever has. Just one. I'll wait.
Don't even get me started on Sylvie or the TVA. 🤮