I tried a few approaches with this, but i do know that dealing with the Schema on any occasion is a bit finicky for want of a better word, Ive updated it to reflect the dob is a date but still hit this error
I had to restart the server after the change and it seemed to do the job, i guess maybe a manual restart is required to kick parse back with the new schema
The server knows about the updated schema through hooks. If hooks are disabled then the server needs to restart to recognize the updated schema. We removed schema pulling some time ago, but we are planning to add it back, see Re-add schema pulling · Issue #8229 · parse-community/parse-server · GitHub.