This new topbar does not work for mobile in its current state.
While the Game Context Menu is open on mobile, undesirable behavior occurs depending on your control scheme.
When using Dynamic Thumbstick, it will freeze up completely in the direction you were moving it in until you let go. If you weren’t moving it at all, it will remain stuck in place and you won’t be able to move.
Similar behavior applies to the regular Thumbstick, but the key difference is that you can still move if it was already in use. Otherwise, it will remain stuck in place and you won’t be able to move.
The only movement more unaffected by this is Tap To Move, but this only because the menu closes itself every time you tap the screen.
Device: IPhone 6s, version 13.3.1