Daisy-chaining cables like that is considered suboptimal but for a GPU like yours it is fine. It can potentially be an issue with more powerhungry hardware so I wouldn't connect a 4090 or a 3090 like that but a 7700XT should be perfectly fine.
So, really, I'd say you're fine as it is and getting a new PSU would only be needed if you plan on doing some heavy overclocking (daisy-chain might cause issues like instability, potentially) or if it just really bothers you. But the GPU will work fine as it is and you won't really see any performance differences.