Doing PCA across frames basically eliminates that. IIRC Pixar did a paper on the technique.
https://renderman.pixar.com/view/denoiser
PCA would be one way to do that. This recent paper suggests that they may be decomposing the samples mostly by path type, though:
https://www.disneyresearch.com/publication/pathspace-decompo...
Doing PCA across frames basically eliminates that. IIRC Pixar did a paper on the technique.