(Regression) Erratic scrolling behavior using the mouse in 6.7.3

After upgrading from 6.7.2 to 6.7.3, I noticed that my mouse's scrolling wheel behavior was very inconsistent in all Qt programs.

At first, I thought it was just my mouse malfunctioning, but after not observing the issue in non-Qt apps (e.g. Firefox), I ran a git bisect in qtbase, between 6.7.2 (good) and 6.7.3 (bad), and I found the culprit commit.

Reproduction steps:

1. Open any Qt program that you can scroll (horizontally or vertically, doesn't matter)
2. Move your mouse cursor on top of the scroll bar
3. Scroll your mouse wheel at any direction, while also moving your cursor in the same direction

Observed results:

The scrolling behavior is erratic; It will sometimes not scroll at all, sometimes "accumulate" scrolls and "jump" a long distance at once, or simply scroll to the opposite direction you intended.

Reproduction video:

(See attached video)