What is Helpful Content Update?
In summary, Helpful content update is an update that reduces the performance of the content written for the purpose of obtaining ranking, which does not help people or does not provide accurate information on Google.
If your site is classified as "useless" because it has low value-added content after the algorithm change, Google may see your site as useless and lower your rankings. To explain with a simple example, if 20% of your site consists of high-quality content and 80% of low-quality content, your entire site can be classified as useless.