Did a bit of investigation.
- Tried toggling vertical alignment on external monitor-> vertical shape in both monitors
- Tried disabling cursor linking to another MacBook -> no effect.
I did notice something interesting. Usually when you have additional monitors, in chrome it prompts you to select the target monitor. Safari also does lets you select the monitor but it uses a hover interface to do so. In orion, it automatically selects the current monitor of the window without prompting for anything.
Just a guess, but this might be caused by how the monitor selection is mapped. It might be defaulting to something to vertical in the absense of a screen selection response. This vertical feels like a good default for meet, as a fallback for mobile sites.