On iPhone (latest updates all around) when entering Edit mode, the Notes field will not let you scroll to the bottom of a longer note (out of view) even if the cursor has been dropped off into that Notes field.
The only way to allow the Notes field to scroll is to make an edit at top, within view. Even just adding or deleting a space. After which you can scroll down to bottom of Note for the real edit you had intended.
Normally dropping your cursor into a window would be enough to get it to scroll and not require the unneeded edit.