I believe the issue Henrick Jeanty reported involved the ability to scroll on a touchscreen from anywhere in the interior of notebook. I think that stopped working with version 14.3, just as he reported. Now, attempting to scroll by touch results in selecting portions of the notebook.
I think the feature you referred to is the scroll bar on the right of the window. That still responds to touchscreen manipulation in ver. 14.3 on my Windows 11 computer as long as nothing has been selected. It seems perverse that even that stops working after a user accustomed to touch-scrolling accidentally selects text. Once touch selection has selected text, I think the user's only option is to go to a keyboard to undo the unwanted selection.
Like Jeanty, I would prefer that Wolfram revert to the 14.2 method of responding to touch in order to conform to the norm used by most other software publishers. That norm makes adaptation to Ver. 14.3 difficult. Adobe Reader is the only other common application I use that even allows users an option to select text by touch the way Mathematica ver, 14.3 now reqires. I doubt many touchscreen users of Adobe choose to enable that option.
I suspect the loss of touchscreen scrolling in ver 14.3 will be especially objectionable for users who are creating things like manipulatables for others to use. Wolfram Cloud now also fails to scroll by touch, at least on an Edge browser. I'm not sure if that was true for before 14.3.
A convention that some publishers use that might satisfy even those who might prefer to select with touch is for touch-swiping to scroll while touch and hold for a second or two opens a touch selection option.
I hope Wolfram looks at this issue.
