Does anyone know what changed w/ the endpoint:

/services/data/v55.0/sobjects/ContentVersion/

On 9/18/2023 we noticed that files were not being uploaded to contact records. I found that the code to upload the files is now returning:

[
    {
        "message": "MediaType of 'application/json,application/pdf' is not supported by this resource",
        "errorCode": "UNSUPPORTED_MEDIA_TYPE"
    }
]

After looking at my test setup in Postman, I got the same result, so something has changed in the Salesforce API... but I can't find any documentation that tells me how to modify the request.

Has anyone else experieneced this, and is there a fix?