Andreas Zeller The reference guide mentions this issue (see the first tip in 10.1).

As Hardy has been saying, there isn't much what we can do here. One possible thing would be to check whether the bean passed to validate() is a Hibernate proxy and then log a warning when validating field constraints on it. But that'd be specific for one JPA provider and generally a bit cumbersome. If you'd like to give it a shot and work on a PR we may include it, though.

Out of curiosity, what's the use case when you run into this? During cascaded validation we wouldn't validate a referenced proxy at all (when using the default TraversableResolver), so you must be passing a proxy explicitly to validate(). It'd be great to learn more about the reasoning behind it.