When using WiFi, your app communicates with the Blynk server and your ESP32 also communicates with the Blynk server. In this case it sounds like you’re using the Blynk cloud servers.
The data is stored on the server, not on your phone or your computer.
The data can be viewed on your phone, probably using the SuperChart widget.
You can download the data to your PC in .CSV format, but with the cloud servers this history download is limited to around 10 days of data. The historical data is still visible in Superchart beyond 10 days (I have some going back two and a half years), it’s just that you can’t download it past 10 days.
Pete.