Is Sentry.setUser safe to be used in a node.js application that handles multiple reqeusts?

I’m trying to setup Sentry on a Fastify / Node.js application and I’m a bit confused about

Sentry.setUser();

This seems to be a “global” function, not attached to a specific transaction.
The Fastify / Node.js application will handle multiple request each being from different user.
Is Sentry.setUser(); safe to be used in this regard? Can there be an issues due to concurrency?