Brand/product reputation and repurchase loyalty
Many reviewers explicitly call it a 'holy grail' or say they've repurchased it 2-4+ times or used it for 1-3+ years, often after trying the original (non-tone-up) ROUND LAB birch sunscreen first.
Desire for a multi-function base/no-makeup product
Buyers purchase it to combine sunscreen, moisturizer, and light tint in one step so they can skip foundation on 'no-makeup' or lazy days.
Value bundle/sale pricing
Several reviews mention buying during a sale or because the 1+1 set offered better value ('cp值不錯', 'good price and quality'), and repeat purchases are often tied to promotions.
Word-of-mouth/social proof
Some reviewers tried it because a friend or family member recommended it or already used it ('A friend said she liked this sunscreen, so I tried it'; buying it for a mother or daughter).
Sensitive-skin-safe sunscreen reputation
Reviewers with sensitive, acne-prone, or combination skin note they sought it out because of its reputation for not causing breakouts or stinging eyes.