Zwift iphone vs ipad vs macos. Different behavior?

I usually ride with Zwift on my iPad or my Macbook Air. combined with a Kickr Core.

On my iPad and Macbook:
When I do regular rides (non-workout)(just a specific route) I use my gears and this feels about right. Going uphill requires to shift gears etc…

On my iPhone:
When I do the same rides, (non-workout)(just a specific route) It doesn’t seem to matter if I shift gears. It just seems to do the same wattage whatever the terrain is. Was thinking about ERG mode being on, but this shouldn’t be the case in normal rides? Also I don’t see any way to enabled/disable this on my iPhone. There’s no ERG mode button available.

Am I missing something?