Instability on Tymeshift API - failed with status code 403 and error message User does not exist

Recently, we started facing an issue with our Tymeshift ingestion pipeline. Some requests began failing with a status code 403 and the error message "User does not exist" randomly—sometimes after a few pages or even at the start of a request. We are using a custom Airbyte connector.

Example request: /wfm/public/api/v1/activities?startTime=1740700799

Any idea?