I’m going to guess you are in the Timezone GMT+8. Server backends work in UTC/GMT, so you set the time in your own local timezone and Strapi converts it to UTC to save in the database.
It will provide the UTC expecting your frontend to convert it to the users timezone. It’s better to handle this conversion client-side as the client is the most trustworthy about what it’s timezone is.
Server backends, including databases, should always always always work in a single standard timezone, typically UTC or GMT+0