Increase in refresh_token_errors after upgrade from 15.1.1 to 16.1.1

We recently upgraded our Keycloak from 15.1.1 to 16.1.1. Ever since we performed the upgrade we’ve started seeing warnings in Keycloak’s logs with the event name REFRESH_TOKEN_ERROR with error=invalid_token.

We haven’t had any reports that users are getting unexpectedly logged out or any other trouble that may be related to the error message.

Is this something we should be concerned about?

Does anybody know of a change in Keycloak 16 that might explain this?