Notice how their tutorial says "run 'dotenvx run -- yourapp'". If you did 'dotenvx run -- env', all your secrets would be printed right there in plaintext, at runtime, since they're just encrypted at rest.

The equivalent in vercel would be encrypted in the database (the encrypted '.env' file), with a decryption key in the backend (the '.env.keys' file by default in dotenvx) used to show them in the frontend and decrypt them for running apps.

The point of encryption is often times about what other software or hardware attacks are minimized or eliminated.

However, if someone figures out access to a running system, theres really no way to both allow an app to run and keep everything encrypted. It certainly is possible, like the way keepass encrypts items in memory, but if an attacker has root on a server, they just wait for it to be accessed if not outright find the key that encrypted it.

This is to say, 99.9% of the apps and these platforms arn't secure against this type of low level intrusion.