The v6.0 branch uses the 3.13.0 python driver, which can't handle DBRef objects that have been shapified by query stats (see PYTHON-4335). We confirmed that things work as expected with later driver versions, but as a workaround on v6.0 we excluded all dbref tests from query stats passthroughs.

We are now see the error on jstestfuzz runs, which we can't just disable or exclude. We should look into actually fixing this issue. Ideally we would upgrade the python driver (at least to 4.0.0), if there are no objections to that. We should be able to use this commit as an example for fixing incompatibilities. 

Alternatively, we could try to catch this DBRef TypeError in run_query_stats.py. I did attempt this but somehow with a naive solution the test infrastructure still knew that the error happened and failed the test at the end, so we may need to do some digging to get it working.