Intermittent 429 errors (rate limit) although no rate limit is defined


We’re using @sentry/nextjs v6.11.0,
We didn’t define any rate limit in the project,
And sample rate is set in the code to 100%:

        dsn: SENTRY_DSN,
        tracesSampleRate: 1.0,

Though, from time to time we see a 429 status code as a response to capturing an event:

What could cause this?

Thanks for the help!