I would like to add that I am using Windows and I have ‘Show text suggestions as I type’ enabled. This setting can be found under Home>Devices>Typing>Hardware Keyboard in Windows Settings. In most text boxes this allows the OS to make spelling and typing suggestions. It believe it actually used to be under the accessibility menu.
The typing suggestions work as intended in small text boxes like the search bar, the quick switch search bar, the command pallet, and when entering a title/name for a note but do not appear when typing into the main body of a note.
I have found that this is a common problem even in Microsoft software and web applications.