Did you just find a file that has a digital signature from Private Internet Access, Inc.? If so, please read on.
You will probably notice Private Internet Access, Inc. when double-clicking to run the file. The publisher name shows up as the "Verified publisher" in the UAC dialog as the screenshot shows:

You can also view the Private Internet Access, Inc. certificate with the following procedure:
Here's a screencap of a file that has been signed by Private Internet Access, Inc.:

As you can see in the screencap above, the Windows OS reports that "This digital signature is OK". This implies that the file has been published by Private Internet Access, Inc. and that the file has not been tampered with.
If you click the View Certificate button shown in the screenshot above, you can see all the details of the certificate, such as when it was issued, who issued the certificate, how long it is valid, and so on. You can also see the address for Private Internet Access, Inc., such as the street name, city and country.
DigiCert SHA2 Assured ID Code Signing CA and DigiCert Trusted G4 Code Signing RSA4096 SHA384 2021 CA1 has issued the Private Internet Access, Inc. certificates. You can also see the details of the issuer by clicking the View Certificate button shown in the screenshot above.
These are the Private Internet Access, Inc. files I've collected, thanks to the FreeFixer users.
| Detection Ratio | File Name |
|---|---|
| 1/68 | pia-service.exe |
| 1/70 | pia-service.exe |
Here's the detection names for the Private Internet Access, Inc. files. I've grouped the detection names by each scanner engine. Thanks to VirusTotal for the scan results.
| Scanner | Detection Names |
|---|---|
| Alibaba | NetTool:Application/SocksSevice.190603 |
The detection percentage is based on that I have collected 138 scan reports for the Private Internet Access, Inc. files. 2 of these scan reports came up with some sort of detection. You can review the full details of the scan results by examining the files listed above.
The analysis is done on certificates with the following serial numbers: