I don’t claim to have discovered this, all credit to this Github post
As a workaround (I assume Cemu/Yuzu is run in gaming mode from Steam):
Press STEAM button Open Controller Settings Edit layout Go to Gyro Select Gyro Behavior -> Directional Pad Choose anything for one of the positions of directional pad. Anything that won’t intefere with using Cemu/Yuzu. I chose Action Sets->Cleared from Parent Now it should work.
That was enough to get Cemu working again. For Yuzu I had to remap the motion sensor. Best way to do that is to follow this video
Cemu I don’t know, for yuzu, what I did was put the yuzu emulator resolution to 1920x1050 (forcingresolution for external display and steam deck display) then navigating to the control menu. Click the motion button, (not the tick one, the one that ask for rebinding the button) then it ask to shake. Shake it! And should be OK.