On March 26, 2020, Living Roots’ rarity was accidentally changed from Common to Epic and the regular card could be disenchanted for 100 dust instead of the normal 5. The disenchantment problem was fixed on March 27 following a server-side hotfix.
What appears to have also happened is that the card was flagged as uncollected even for those who still have it. This causes Living Roots to be found even if there are still other missing commons.