Yo

The balancing philosophy of BHVR is a 60% kill rate. They want killers to be the power role. So in that sense, the game is pretty balanced.

What you described however sounds more like you should follow @Lost_Boy's advice and take a break. Because it seems like you cannot get any enjoyment out of it at the moment. Many long time players have done it. I regularly go a few days or sometimes weeks without playing DBD. When you come back, you'll find that the game is far more fun again.

Hitboxes haven't been touched in a while, so that part is probably induced by latency. On your screen it may look like the killer looks in a different direction or you're already way past a window but from the killer's perspective it looks like you are right in front of them. And since the killer can only play around what they actually see on their screen, it makes sense that latency favors them. We had a time when BHVR tried to turn this in the survivor's favor and it led to survivor queue times sky rocketing (20+ minutes at times) because nobody wanted to play killer and constantly feel robbed. The game gave you the feedback that you had hit a survivor but they were still healthy.

Pallets also weren't touched over the last years. So that is likely latency again. Or maybe your keyboard or controller has an issue? It's definitely not something the devs have changed.

The perks you listed were highly problematic. Boil Over was so strong that the only way to avoid it was slugging when survivors went down in specific spots. That wasn't exactly fun to play against. DH was by far the most controversial perk in existence and it's good that it was nerfed. It was highly overused (75% pick rate in high MMR), way overpowered and worse it was guaranteed to give you value. It was so bad, that killers would wait out DH on every survivor even when they didn't have it because the risk was too high. That can never happen again. DH deserves its downfall. MfT bridged 20% of the speed difference between killers and survivors. That was too much. Even just the numbers alone were enough to know that this would be unfair. And unfair it was. There was pretty much no way to outplay any of the safer tiles in the game without a strong chase power. Adrenaline has 2 issues.

1) It incentivises slugging since a slugged survivor is only healed to injured and a hooked survivor is healed to healthy.

2) It wakes you up against Freddy, which leaves him with literally no power.

There are still plenty strong survivor perks. Like SB, Lithe, WoO, Deja Vu, Resilience, Unbreakable, OTR, Bond, Resilience and Hope to name a few of them.

Tunneling is an issue on its own. One that isn't exactly easy to fix. DS will receive a buff, so that could improve this situation a bit. Although it will probably take more than that to stop excessive tunneling.

Anyway, I suggest you take a break too. Just for a few days or a week. Come back when you really feel like playing DBD again and your matches will be a lot more enjoyable.