scroll-axis-lock is a CSS property that authors can use to instruct browsers not to constrain a user's scrolling gesture to one axis. Web browsers often "lock" a user's scrolling gesture to a single axis when that gesture starts with significantly more movement in one axis than in the perpendicular axis. In many cases, this behavior improves the user's experience by avoiding accidental scrolls along the perpendicular axis when the user's intent was to scroll only one axis. However, in cases where an author wishes their element to always be diagonally scrollable, this locking behavior forces the user to start their gesture at an angle that doesn't trigger the locking, often not in alignment with the author's intended user experience.
Explainers: https://github.com/explainers-by-googlers/scroll-axis-lock