Content Type being inferred from file name only (api) (workaround?)

I am currently trying to be a photo review tool for my team. I am using the API to create the records in airtable with an attachment field. The attachment files live on S3 and have proper content type set there but do not have a file extension in the url. When I use the api to create the object Airtable doesn’t recognize the file as a jpeg for instance. I tried sending type through in the attachment array but I received INVALID_ATTACHMENT_OBJECT (because, like the documentation says, type is not allowed).

Is there a work around for this issue?