I see this a lot, not a recent regression, but I never filed it. On fennec if I'm at the rightmost edge of a page (that's scrollable on both axes) and move my finger towards 7 o'clock (down and slightly to the left) then the page moves up (coreect) and slightly to the left (wrong). It's quite noticeable if you're at the rightmost edge of the page because you end up drifting away from the edge.
Bug 1509295 Comment 0 Edit History
Note: The actual edited comment in the bug view page will always show the original commenter’s name and original timestamp.
I see this a lot, not a recent regression, but I never filed it. On fennec if I'm at the rightmost edge of a page (that's scrollable on both axes) and move my finger towards 7 o'clock (down and slightly to the left) then the page moves up (correct) and slightly to the left (wrong). It's quite noticeable if you're at the rightmost edge of the page because you end up drifting away from the edge.