If you enable EventHandlerDrivenSmoothKeyboardScrolling, scroll using the keyboard, then immediately after use the trackpad to scroll, the webpage will scroll back to the position where the keyboard scroll left off.
<rdar://problem/99101109>
Pull request: https://github.com/WebKit/WebKit/pull/3623
Pull request: https://github.com/WebKit/WebKit/pull/4016
Committed 254561@main (8c822fa15adb): <https://commits.webkit.org/254561@main> Reviewed commits have been landed. Closing PR #4016 and removing active labels.