There's always something that's the bottleneck, it just moves from one component to the another. The 4070Ti should be a perfectly good card for 1440p gaming, and isn't going to be held back by a 9-series CPU. You could probably get about the same gaming performance from a 4070Ti with a 7-series CPU, but it depends on the game. Having a bit of overkill in the CPU isn't a bad situation to be in, and can make gaming a bit smoother by being able to cope with Windows doing stuff in the background (for example).
Having a 9% bottleneck when switching to a 1440p monitor is not necessarily a cause for concern, and it's important to understand the context and implications of this bottleneck.
Firstly, a 9% bottleneck means that your CPU (i9-13900k) may be limiting the performance of your GPU (RTX 4070 Ti) slightly when you upgrade to a higher resolution monitor (1440p). In practical terms, this could mean that in some scenarios, your CPU might not be able to keep up with the demands of the higher resolution, resulting in slightly lower frame rates or performance in certain games or applications.