I'm confused why you would think so. Did you mix up your links? The paper you link to replaces the quick-and-dirty 3D-to-2D approximation used in Gaussian splat

I'm confused why you would think so. Did you mix up your links? The paper you link to replaces the quick-and-dirty 3D-to-2D approximation used in Gaussian splatting with more physically accurate rendering using Monte Carlo path tracing. FreeTimeGS uses Gaussian splatting for 3D scenes with movement. Both descend from (and cite) 3D Gaussian Splatting for Real-Time Radiance Field Rendering https://arxiv.org/abs/2308.04079 https://arxiv.org/abs/2308.04079 but take it into entirely different directions.