My work laptop is connected to my router via ethernet and personal laptop is connected via wifi to same router. Whenever I switch my vpn on on my personal computer, the connection icon becomes that of the ethernet connection (but has no hardline connection). Is there crossover somehow and my activity is able to be seen by my employer even on my personal laptop w a vpn running?
No, your employer won't be able to see what you're doing on your personal network.
When you mount the VPN on your personal laptop, your network connection icon change to the same "wired network" icon. I believe this is because your VPN client emulates a physical adapter, and the Windows OS doesn't make the difference with a wired connection.
I couldn't find a source from Microsoft explaining why it was built this way and whether this is considered an expected behavior.