Patching the game through steam is very slow

This is something that has irked me for a long time but I didn't get around to posting about it. When updating the game using Steam the game takes a very, very long time to patch. In fact it is to the point where it is faster to uninstall and reinstall the game again on my system. I timed the update today and it took a whole 20 minutes and 16 seconds. Meanwhile reinstalling took a total of 4 minutes and 35 seconds.
My PC has an AMD Ryzen 7 5700X, 32 GiB of RAM, 1 Gbps internet and the Steam library is located on a Gen4 M.2 SSD so I don't think it should be this slow.

 

This is because steam's patching system is VERY inefficient, and the total disk written per patch is actually more than twice higher than the game's full size, hence the long patching time compared to re-installing the game. It's also bad for your SSD due to the higher write amplification. That's more on Steam not Beam as I experience the same problem in Euro Truck Simulator 2.

However, in theory, as stenyak said that not compressing the game makes patching smaller, but could anyone explain that why in reality often the opposite is true (ETS2's pack is also uncompressed IIRC)?
For reference my last game update the patch was 49.1GB and the time used is somewhere between 4 minutes and 35 seconds and 20 minutes and 16 seconds