Premature low/critical battery warning

My battery levels on P3A were set as-

Was flying out of sight and Low battery warning displayed at 32% during RTH

Critical battery kicked in and began auto land at 22% and was a good half mile from Home point.

Fortunately I retrieved it with no damage but why did critical auto land initiate at 22%!!

Battery is new, 20 cycles and good health across cells

Are you sure those were the current levels? Have you checked them?
Sometimes they get reset with a firmware upgrade.