As @jamesstaddon mention in a post about 7 years ago
Here’s a great article on how to shoot and combine star trails: https://petapixel.com/2013/03/18/how-to-photograph-star-trails-from-start-to-finish/ (I recommend you have AdBlock Plus installed for that website)
If shooting in Bulb, it’ll take a lot of experimenting. You’ll need 30min to an hour at least. This is rough on your camera. And if your tripod gets bumped for whatever reason, or your battery runs out….oh well, you have to start over.
The safest way to go about creating nice long star trails is to stack many, many 30sec exposures. It’s very simple. In Photoshop, it’s a matter of setting each layer to the Lighten blend mode.
THere are probably actually star-trails in your picture (although without having the raw photo to work on I can’t prove that), but you have so many hot pixels and ISO noise that you can’t see them.