They already rate one star even the drama hasn’t air yet.
I just found out last week when zhao lusi's gen z drama only 3.9/10 rating on douban with 65% rated 1 star. it turns out not only gen z, but almost all lusi dramas are rated 5 and bellow. So, a fanclub's member in china told me the sites like douban and bilibili can be manifested, lusi's agency is a small agency, they only knew how to earn money and invests lusi to earn more money but they abandon lusi's reputation from sites like douban. Because douban is one of the most expensive sites, if you are willing to pay high price to fix the rating then it will be fixed. Including water armies (to vote and to comments). Therefore, most of big agencies have budget to buy water armies to defend their actors. This is why when we read the comments section in douban, we will find so many repeating lines (it was like automatic users' comments). They said it depends on the agency now if they're willing to pay or abandon the dramapage.