This is a relatively common issue, especially if you have a mechanical hard drive (though it does sometimes happen on SSDs). I've found that the easiest way to fix it is to pause and then unpause the download every time that happens. If that doesn't help, try pausing the download, then exit Galaxy. After that, wait a few minutes to make sure all the background processes closed as well, then restart Galaxy and see if that helps. If none of that helps, try rebooting your PC and then do those tips if it still isn't going any faster.

The reason this tends to happen with Cyberpunk is because of how the game is built and how the data flow works with Galaxy. Galaxy doesn't install/patch games quite like Steam does. It moves a LOT of data around and (particularly on a mechanical hard drive) this means it'll take a while, especially if you don't have at least 15% free space available on your drive.

also limit your Galaxy download speeds in settings to 1/2

so if your average internet speed is 60 mb/s when downloading limint Galaxy to 30 mb/s... this will give you a stable network conection

My average Internet speed is about 37 MB/s. I limit Galaxy to 20 MB/s and still get 0.1 MB/s downloading speed with actual speed far below 0.01 MB/s. For example, a 6 MB file takes HOURS to download.

Sometimes Galaxy shows something like 5 MB/s speed but downloaded size is still for hours. A 6 MB file with 5 MB/s speed shown takes 5 hours to download.

Web download is way faster than Galaxy.

I personally haven't had issues to anywhere near this degree while using the latest 1.2 version (since 2.0 is still nowhere near release ready). That said, even when sticking to the last known stable version of Galaxy, the web downloaders will download faster. This is because Galaxy, like other launcher apps, runs concurrent download and update/install processes, which extends the time estimated (and taken) for a download beyond just the time which is spend on the actual downloading part of the process. Web downloads only count the time to download the file, then you separately extract it to install/update the game, which runs on its own timer (and usually uses a more efficient process that takes less time than the install and update processes used by Galaxy).