The reference section of the datasheet refers to REFout, not REFin as you had
guessed.
The input range adjustment tracks variations on REFin linearly (±5% of 1.25V).
Don’t exceed REFin by 1.25±5%.
REFin | Input Range
1.19V | 0.97V
1.25V | 1.0V
1.31V | 1.08V