That's true in general of many Western pharmaceutical companies. However, in the case of China's pharma, there isn't such an onerous record of selection bias. There's a lot of evidence that Pfizer played around with numbers to get to those high 90+ percent vaccine efficacy figures. The debate over how "useless" China's vaccines are stems largely from their comparatively low efficacy after 2 shots. However, what isn't mentioned nearly as often is the T-Cell response China's vaccines elicit after COVID infection, which is far superior to MRNA vaccines. If this evidence holds true, then it's likely that after all is said and done, the death rates in China will be significantly lower than those places that only took mRNA vaccines.
Why does not China advertise how their vaccines are far superior to mRNA vaccines?