I'm having a recent issue, as recent as the PS 2023 release, where after editing RAW files and saving as PSDs the files size is increasing x10. For example the recent edit I did was a 25.3MB RAW file. The finished product was a simple single layer, cut out background with a clipping path, the saved PSD file is 245.8MB. Is there a reason the PSD file size is exponentially larger? Most of the images im working with are 1-2 layer product images.
A raw file is a single channel at 12 or 14 bit depth, An RGB file is three channels at 16 bit depth. So that alone triples to quadruples the file size. Another layer can up to double that again, and if you use smart objects there's huge overhead, and the size increases further.
You should also be aware of compression. A PSD or TIFF can be compressed or uncompressed. And if you compare to a jpeg, the sizes aren't even in the same neighborhood. Jpeg compression shrinks the size dramatically - but at the price of permanent degradation.