Anyone figured out how to get rid of that bar that drops down from the top in Windows 365?

Unpinning the connection bar makes it auto-hide, but it still reappears when your pointer reaches the top edge—that’s the behaviour you’re describing.

For Windows 365 through Windows App, I’m not aware of a supported setting or policy that completely disables that hover-triggered bar. Registry tips for the older Remote Desktop client (mstsc) shouldn’t be assumed to work in Windows App.

The practical workaround is to use the Cloud PC in windowed mode, then maximise that window. It changes the full-screen experience, but avoids the drop-down bar over your remote apps.

If you need full-screen mode without the hover bar, submit that specifically through Windows App’s feedback option. It’s a different request from simply allowing the bar to be unpinned.