Well, from my view, that's kind of the central tension, isn't it? The 'dark side' bits, whether it's his raw rage during the Overhaul arc or the glimpses we get with Blackwhip, they don't feel evil to me so much as primal. They're a product of the incredible pressure he's under and this inherited power that's fundamentally volatile.
What it does is fracture his relationships, but not by turning him into a villain. It makes All Might and the others terrified for him, not of him. They see a kid pushing himself toward self-destruction. The dynamic with Bakugo shifts most, I think—from pure contempt to a grudging, worried recognition that Deku is now wrestling with forces just as dangerous as his own explosive temper. It creates this awful distance because he starts hiding his pain, trying to shoulder All For One alone, which is the exact opposite of what a hero in that world should do.
In the end, it's less about an 'evil side' corrupting bonds and more about the trauma of the burden threatening to isolate him completely. The latest chapters show the real damage is to the trust his friends had in being able to share his struggle.