A low strength druid has been hit twice by a Shadow's Strength Drain ability, reducing their strength score from 9 to 3. Fearing potential instant death, the Druid uses Wild Shape to turn into a Brown Bear, changing their physical ability scores to match that of the Brown Bear, which would normally mean their strength is now 19. What happens to the reduction to strength score? The only official information on this matter comes from Sage Advice:
Can a creature under the effects of polymorph have other spell effects on them, or are those game statistics also replaced by the those of the beast form? Polymorph replaces only the target’s character sheet or stat block with the stat block of the chosen form. Other effects, such as other spells, still exist.
However this only covers what could happen if a creature already polymorphed has an effect placed on them. In this instance, would the Druid in Brown Bear form have 19, 13, 3, or something else as its strength score? Would the result be the same for Polymorph, or other shape-changing abilities that take the new form's statistics?