I suspect that your crashing issues and your delayed action issue when deleting files are related. Neither should be happening; the macOS does not crash randomly and all the iCloud synch happens in the background and should never affect usability.

For the job you got your Mac for, did it use a VPN by chance? It's possible that you are still connecting to that VPN depending on how you configured your network settings. When you migrated from the work Mac to your personal Mac you may have brought over all the settings and configurations you used on the work Mac to the new machine.

It could also be something in your local network. Do you have a robust firewall or other security device between you and the internet? You may be experiencing some issues related to the firewall blocking some of the connections the Mac is trying to establish; or vice versa if you're using some kind of 3rd party storage solution or something similar.

Anything else "weird" about your network config? Are you using a mesh network, some kind of nonstandard WiFi, a MiFi cellular connection or something else? If there is something unusual about your setup I would investigate that as a potential source of problems.