It is not so clear anymore what this check must be doing.

jwt.verify is called on a static string, or a string from the environment.

If anything, that first choice seems a bit unsafe. Would that be the idea of this check?

Possible problems:

https://auth0.com/blog/critical-vulnerabilities-in-json-web-token-libraries/

Without the algorithm, this code seems to be broken if a public key is used.

It seems hard to exploit in this case, because there is no sign of which algorithm is used, and there is no code to have this snippet sign something for you to get the public key.