I want to hear what other people have to say, but I also want to say how hard the devs missed on these buffs.
The issue here is most of Slade's buffs are to his killpower. While sure, Slade is struggling to kill, his killpower is not the cause here. Slade can kill once he is able to get in and combo someone. He has great tools in down air, forward air, and grounded up special, which all can secure kills fairly easily. The tools he has to catch off guard opponents at higher percents did get buffed a bit, like up air and neutral air, but all of these buffs amount to about 5% earlier kills. The actual impact of these changes is incredibly small. Not only that, but the only times where I saw discussion on Slade's killpower, it was in reference to his strong attacks. Uncharged strong attacks won't start killing until over 120% without DI on pretty much any stage. Buffing any of these doesn't have great impact though because Slade desperately struggles to get in.
I just kind of assumed everyone knew Slade needed to have his core gameplan buffed. He has an incredibly hard time getting items and equipment. He is just too slow to do anything without items which means you're spending money on items to just to have a chance in neutral. You have decent aerials to wall people out with but you still need them to approach you, which turns a lot of Slade matches into waiting games. His advantage state contradicts the money mechanic, because while he has good tools in advantage, money often despawns or falls of the stage while you are in advantage. Currently the money mechanic just feels like it is holding Slade back, and I'd rather have neutral and down special to be anything else at this point. Any changes to his movement speed or money would be appreciated though, it doesn't have to be a full rework.
I have some other specific gripes with Slade, like how his items feel less innovated on than Ultimate and P+. Z drop aerials being removed makes items feel way less impactful, and more strict aerial glide toss feels weird. Not to say that RoA2 should copy these, but nothing was added to items to make them feel improved. The devs can be incredibly creative but they just fell short here. I don't want to give suggestions because a lot of my ideas are surface level and are just something to change things for the sake of change, not really to innovate or make the game more interesting.