I don't use cashback, not familiar with it, but the first one that comes to my mind is Expressbonus
https://www.expressbonus.com/en/shops/
electronics/aliexpress/ with Aliexpress (the largest online retailer in china).
Also, I heard about TinkOff
https://alipro.site/12-cashback-on-
aliexpress-if-payment-is-made-by-
tinkoff-pros-and-cons/ and cashbackcloud.com
https://cashbackcloud.co/. A common one seems to be RebatesMe
https://www.rebatesme.com/ they seems to have a pretty large customer _base_ in China for cashback. offering a pretty high cashback rate for around 3000 online shops.