By choosing to deploy to your VPC, you handle any security/privacy/GDPR requirement. Upsolver will manage its servers in your VPC but won't have any access to your data.
If you don't want to manage servers, this is the right deployment for you. By choosing to deploy to Upsolver VPC, you remain completely serverless. Cluster management and scaling won't require any of your attention. Your data will be stored only in your S3 bucket. For data processing, Upsolver copies your data to RAM and then writes it back to your S3. No data is stored on disk in Upsolver's VPC.