It all boils down to difference in the amount of real estate (screen size) that is available horizontally.
And your last screenshot shows why I no longer use the side bar. I have always been in favour of the sidebar (see Is the side bar ready for prime time?) till June 2024 (see Layout changes not an improvement)
I now only use it to store references and links to useful sites and open it if needed.
Note
I don't use an iPad/iPhone.