It seems that Google was originally developing the Pixel 5 with its Tensor SoC, rather than the Snapdragon 765G. The device, codenamed 'whitefin', contains an earlier revision of Tensor with different clock speeds than the SoC in the Pixel 6 series, too.
https://www.notebookcheck.net/Google-had-a-smaller-Pixel-smartphone-with-a-Tensor-SoC-in-development-possibly-the-Pixel-5.578721.0.html