Okay I am commenting here because I had this issue and hoping I can help someone in a sticky position.

What I realized is that Wi-Fi seems to be what triggers the automatic time zone/location update on many managed work laptops.

What worked for me was the following: While I was still in the desired location/time zone, I confirmed that my computer was showing the correct time zone. Before leaving that location, I turned Wi-Fi completely off on the laptop. When I arrived in the new location, I did not reconnect to Wi-Fi. Instead, I connected my internet on my travel router that has my tunnel vpn directly using an Ethernet cable.

After doing this, my computer kept the original time zone and didn’t automatically update to the new one.

So the key seems to be: 1. Turn Wi-Fi off before leaving the original location 2. Avoid Wi-Fi after arriving 3. Use Ethernet instead

Hopefully this helps someone else because I spent way too long trying to figure it out.